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.