# ChatGPT custom instructions: how to set them up > Set ChatGPT custom instructions in Settings, Personalization. See the character limits, how to turn them off, and what they do and do not change. https://www.kortex-notebooklm.com/tutorials/how-to-set-custom-instructions-in-chatgpt 1. [Tutorials](/tutorials) 2. ChatGPT custom instructions: how to set them up # ChatGPT custom instructions: how to set them up 3 minutes 6 steps Updated November 10, 2026 ## Quick answer On the web, open Settings, then Personalization. Make sure Enable customization is on, then type your instructions in the Custom Instructions field. They apply right away to all chats, including existing ones. Free and Go accounts can save up to 1,500 characters. Plus, Pro and work plans can save up to 5,000. ## Watch it first ChatGPT custom instructions: how to set them up Read the transcript Custom instructions tell ChatGPT how you want it to answer. Here's how to set them up. First, decide what to write. Good instructions are plain and stable: your role, the tone you like, and the format you want. Keep temporary needs for the chat itself. On the web or the desktop app, open Settings, then Personalization. On the iPhone or Android app, open Settings, then Customize ChatGPT. Make sure Enable customization is switched on. If it's off, ChatGPT won't use what you write. Type your instructions in the Custom Instructions field, in short, clear sentences. For example: Explain things in plain English. Keep answers under 200 words unless I ask for more. Then start a new chat and ask something you often ask. If the answer isn't what you wanted, edit the text and try again. To turn them off, go back to Personalization and switch off Enable customization. You can also delete the text from the field. Set them once, and adjust them any time. Full steps and fixes are on our tutorial page. ## What you need - A ChatGPT account, signed in at chatgpt.com. Custom instructions are on all plans. - A few things you wish ChatGPT did every time, such as a tone, a format or your role ## On this page 1. [Decide what to write](#step-1) 2. [Open Personalization](#step-2) 3. [Turn on customization](#step-3) 4. [Write your instructions](#step-4) 5. [Test it and adjust](#step-5) 6. [Turn them off or delete them](#step-6) 7. [If it doesn’t work](#trouble) 8. [Questions](#faq) 1. ## Decide what to write Custom instructions are anything you want ChatGPT to consider in its answers. Good ones are plain and stable: your role, the tone you like, the format you want. Keep temporary needs for the chat itself. 2. ## Open Personalization On the web or desktop, open **Settings**, then **Personalization**. On the iOS or Android app, open **Settings**, then **Customize ChatGPT**. 3. ## Turn on customization Make sure **Enable customization** is switched on. If it is off, ChatGPT will not use what you write. 4. ## Write your instructions Type them in the **Custom Instructions** field. Use short, clear sentences. For example: Explain things in plain English. Keep answers under 200 words unless I ask for more. Stay inside the limit: 1,500 characters on Free and Go, 5,000 on Plus, Pro, Enterprise, Business and Education. 5. ## Test it and adjust Start a new chat and ask something you often ask. If the answer is not what you wanted, edit the text and try again. Changes apply at once across all chats, including existing conversations. 6. ## Turn them off or delete them Return to **Personalization**. Switch **Enable customization** off. You can also delete the text from the fields. Updates affect future conversations only, not old ones. ## If it doesn’t work ChatGPT ignores my instructions Check that Enable customization is on. Inside a project, project instructions apply and override your global custom instructions. Shorten the text and make each line one clear rule. I hit the character limit Free and Go accounts can save 1,500 characters. Plus, Pro, Enterprise, Business and Education accounts can save 5,000. Cut long examples and keep only the rules you need. Old chats still show my previous instructions Updates apply to future conversations only. To remove instructions from previous conversations, clear those conversations from your chat history. ## Questions people ask Something we missed? [Ask us](#contact). ### What is the difference between custom instructions and memory? Custom instructions are guidance you write and control. Memory can use relevant information that builds up across conversations. See [how to turn off ChatGPT memory](/tutorials/how-to-turn-off-chatgpt-memory). ### Do custom instructions work inside Projects? Project instructions apply only inside that project and override your global custom instructions. See [how to use ChatGPT Projects](/tutorials/how-to-use-chatgpt-projects). ### Will people see my custom instructions if I share a chat? No. OpenAI states that your instructions are not shared with shared link viewers. ### Is there an API for custom instructions? No. OpenAI says the Chat Completions API uses system messages for a similar effect. ## Sources - [ChatGPT Custom Instructions (OpenAI Help Center)](https://help.openai.com/en/articles/8096356-chatgpt-custom-instructions) , checked November 10, 2026 - [Projects in ChatGPT (OpenAI Help Center)](https://help.openai.com/en/articles/10169521-using-projects-in-chatgpt) , checked November 10, 2026 ## Keep going [Chat Library Keep your AI chats on your computer and search them, next to your YouTube videos and notebooks.](/features#organize) [Kortex docs The full reference for this feature, with every option.](/docs/chat-library) ### More tutorials - [How to share a ChatGPT conversation with a link](/tutorials/how-to-share-a-chatgpt-conversation) - [How to share a Claude chat: public link or invite by email](/tutorials/how-to-share-a-claude-chat) - [How to turn off ChatGPT memory (and delete saved memories)](/tutorials/how-to-turn-off-chatgpt-memory) - [How to upload a PDF to ChatGPT and ask questions about it](/tutorials/how-to-upload-a-pdf-to-chatgpt) [All tutorials](/tutorials) ## Do it on your own notebooks. Install the Kortex extension and follow these steps on a notebook you already have. [Add to Chrome](https://chromewebstore.google.com/detail/kortex/hdapplggdhndkblofffknpmnnnnbncbn) 100,000+ users, rated 4.5 on the Chrome Web Store.