How to make AI remember how your business works: instructions, projects, GPTs, Gems and skills

Write it down once in a place the AI reads every time. AI assistants start each chat without knowing your shop or office. There are three ways to fix that. Custom instructions in your settings apply to every chat. A project is a workspace with your own files and instructions, available in ChatGPT and Claude. A custom assistant is one you build once and reuse: a GPT in ChatGPT, a Gem or skill in Gemini. Put in your tone, your products, your price list and your rules. Leave out customer data and passwords. The menus below were checked on the makers’ help pages on 3 November 2026, except where the text says a page could not be read.

This site is written with AI tools, including Claude by Anthropic. This page uses only what makers, public authorities and published studies say, with links.

This is lesson 5 of the free course “AI for small business”. Lesson 4 gave requests to copy; this lesson saves you from retyping the background every time.

Which option fits your business?

What you want	Use	Where you find it
The same tone and basic facts in every chat	Custom instructions	ChatGPT, Claude, Gemini, Microsoft 365 Copilot
One job with its own files, such as customer emails with your price list	A project	ChatGPT, Claude; Microsoft describes Copilot Notebooks for the same purpose
A ready-made helper that colleagues can open and reuse	A custom assistant	GPTs in ChatGPT, Gems and skills in Gemini
The AI recalls things from earlier chats on its own	Memory	ChatGPT, Claude, Microsoft 365 Copilot; in Gemini, remembering details is limited to the US and to Google AI plans; you do not control exactly what it keeps

Memory is convenient but not reliable for business facts. OpenAI’s help article on memory, in a copy read on 31 October 2026, says memory “does not retain every detail from every conversation” and that ChatGPT decides what is relevant. Prices and rules belong in instructions or files you write and can replace.

What should you write in the instructions?

Short, concrete sentences work well. A template to adapt:

We are [business name], a [type of business] in [town]. Our customers are [who they are]. Write in [language], in a [warm and direct / formal] tone. Use “you”, short sentences, no slang. Our products or services: [list, or “see the attached file”]. Prices: use only the attached price list dated [date]. If a price is not in it, say you will check. Opening hours: [hours]. Contact: [shop phone or email, not a personal one]. Rules: never promise discounts, refunds or delivery dates. Never give legal, tax or medical advice. If you are not sure of a fact, say so. Format: emails under 150 words, with a greeting and our signature: [signature].

Add files for the details that change: a price list, a product sheet, your returns policy, a style guide. Write the date in each file’s name, such as “price-list-2026-11”, so you can see which one the AI is using.

What should you leave out?

Customer, patient or staff data. Instructions and project files are read in every chat, and on business plans they can be shared with colleagues.
Passwords, access codes, bank details.
Secrets you would not show a new employee on day one.
Old prices. Replace the file when prices change; do not just add a new one next to it.

Files stay stored until you delete them. OpenAI’s retention article, in a copy read on 31 October 2026, says files in a custom GPT are kept until the GPT is deleted, and files in a project until the project or file is deleted. On personal plans, the makers’ training settings apply too: OpenAI’s memory article says it may use chats and remembered information to improve its models while “Improve the model for everyone” is on. What happens to what you type shows each setting.

How do you set it up, assistant by assistant?

The assistants are in alphabetical order.

ChatGPT (OpenAI)

From OpenAI’s help pages on custom instructions and projects, read on 3 November 2026:

Instructions for every chat: on the web and desktop, Settings, then Personalization; check that personalization is switched on and write in the Custom instructions field. In the phone app, Settings, then Customize ChatGPT. OpenAI says they apply at once to all chats.
A project: select “New project” in the sidebar and give it a name. To add instructions, open the more options menu (•••), then “Project settings”. OpenAI says project instructions apply only inside that project and override your general custom instructions.
Memory: Settings, then Personalization, then Memory, according to the memory article read on 31 October 2026.

Limits: OpenAI says projects depend on “plan availability and workspace settings”, and the number of files depends on your plan. Chats made with a custom GPT cannot be moved into a project. The help article on creating GPTs could not be read, so no steps are given for GPTs; the Italian pricing page, in a copy read on 31 October 2026, lists “GPT personalizzati” among the features of Plus.

Claude (Anthropic)

From Anthropic’s help pages on personalization, projects and memory:

Instructions for every chat: click your initials at the bottom left, then Settings, then Your Claude, and write under Instructions.
A project: click Projects, then ”+ New Project”, give it a name, then “Set project instructions” and “Save instructions”. Add files with the ”+” button in the project’s knowledge area.
Memory: Settings, then Your Claude, switch “Generate memory from chats”. Each project has its own memory.

Limits: free accounts can create up to five projects, and Anthropic’s personalization page calls project instructions a paid-plan feature while its projects page says projects are open to all users. On Team plans memory is off for each member until they switch it on.

Gemini (Google)

Gems are changing. Google’s transition page says that on 17 November 2026 Gems on personal accounts of people aged 18 or over turn into skills and become read only: you can still see them but not use or edit them. They are removed on 17 December 2026. Workspace business accounts follow in March 2027. Existing Gems are converted automatically.

A skill (personal accounts, 18 or over): on gemini.google.com, in the sidebar click Customize, then Skills, then Create, then “Create manually”. Paste a name, a description and the instructions.
A Gem (personal accounts until 17 November 2026, Workspace business accounts until March 2027): click Open Sidebar, then Gems, then New Gem; write a name and instructions, add files under Knowledge with Add files, then Save (Google).
Instructions for every chat: on gemini.google.com, at the bottom click Settings, then Personal context; under “Your instructions for Gemini”, click Add (Google). Google says all users can add instructions; Gemini remembering details from your chats on its own needs a personal account, age 18 or over and a Google AI plan, and for now works only in the US.

Microsoft 365 Copilot (Microsoft)

From Microsoft’s help page on custom instructions:

In Copilot Chat, signed in with your Microsoft 365 account, select ”… Settings and more”, then “Chat settings”, then Personalization.
In the “Custom instructions” tile, select “Edit instructions”, write them, then “Save instructions”.
Memory: Microsoft says Copilot Memory saves details such as preferences from your chats, and that you delete a saved memory from Chat settings (Microsoft).

Microsoft’s business page also describes Notebooks, which keep a project’s content in one workspace; which plans include them was not checked for this lesson.

Other assistants

Mistral’s pricing page lists up to 1,000 project folders on its Vibe Team plan. Its help pages for these features were not found on 3 November 2026, so no menu names are given.

How do you keep it up to date?

Once a month, reread your instructions and replace any file whose prices, hours or products changed.
Test with a known question, such as “How much is [product]?”, and check the answer against your list.
Look at the memory and delete anything wrong or out of date.
On a business plan, decide who may edit shared projects and assistants, so one person keeps them right.

Where to go next

Lesson 4: ready-made requests for your trade gives requests that work well with fixed instructions.
Lesson 3: plans and costs explains which plans let colleagues share projects.
AI assistants compared puts the assistants side by side, plan by plan.
AI for everyone is the complete guide to today’s AI, from the start.

Quiz: check what you learned

Pick one answer for each question: you see at once whether it is right, and why. Your answers are not sent anywhere.

Where should you keep your current price list so the AI uses it?
Show the answer
Right answer:B. In a dated file added to a project or custom assistant, replaced when prices change
A file you control is read the same way every time and can be replaced; memory is picked by the AI and may miss or keep old details.
Which of these does NOT belong in fixed instructions?
Show the answer
Right answer:C. A customer's name and phone number
Fixed instructions are read in every chat and may be shared with colleagues; customer data never goes in.
What happens to Gems on personal Google Accounts from 17 November 2026?
Show the answer
Right answer:A. They turn into skills and become read only
Google's help page says Gems on personal accounts of people aged 18 or over transition to skills on that date and are removed on 17 December 2026.
In Claude, what does a project give you that profile instructions do not?
Show the answer
Right answer:B. Its own files and instructions, used only in that project's chats
Anthropic says project instructions apply only to chats within that project, and files in the project knowledge are used across the chats in that project.

Common questions

What is the difference between custom instructions and memory?

Custom instructions are what you write yourself: the AI reads them in every chat, word for word. Memory is what the AI picks up from your chats on its own; OpenAI says it does not keep every detail and decides what is relevant. For prices and rules, use instructions or a project file, which you control, not memory.

Are Gemini Gems going away?

Yes, for personal Google Accounts. Google's help page says that on 17 November 2026 Gems on personal accounts of people aged 18 or over turn into skills and become read only, and they are removed on 17 December 2026. Workspace business accounts follow in March 2027. Existing Gems are converted automatically, and you can also recreate them as skills by hand.

Can my colleagues use the same project?

On business plans, often yes. Anthropic says Team and Enterprise projects can be kept private or shared with the organisation, and OpenAI's help pages describe shared projects in ChatGPT workspaces. On personal plans, each account has its own projects. Lesson 3 of this course explains the business plans.

Topics: AI for small business, custom instructions, ChatGPT projects, Claude projects, custom GPTs, Gemini Gems, Gemini skills, Microsoft 365 Copilot, memory