Say you find yourself typing "keep this short" or "plain English please" at the end of every single ChatGPT question. Here's how to set custom instructions in ChatGPT once, so it just remembers your preferences from then on.
What actually belongs here
Custom instructions are for preferences you repeat constantly — tone, length, how you want uncertainty handled — not for one-time project details. Think of it as a small standing note: plain US English, short checklists, state your assumptions upfront. That's the practical step worth doing today, since it saves you retyping the same request forever.
Keep anything private out of it — no passwords, account numbers, or client names. This is a note about how you want help, not a place to store information ChatGPT doesn't need.
Where to find it
On web or desktop: your profile menu → Settings → Personalization → Custom Instructions. On iPhone or Android: the side menu → Settings → Customize ChatGPT. Labels shift sometimes, so OpenAI's Custom Instructions help article is worth a look if your screen looks different.
A draft you can copy
Here's a solid starting point:
Write in plain US English. Start with the direct answer, then a short checklist when useful. Keep routine answers concise. State important assumptions and flag anything that needs verification instead of guessing.
Change the wording to match how you actually talk. Just avoid contradictory instructions like "always be brief" and "explain every detail" in the same breath — pick one default, and ask for the exception when you actually need it.
Test it before trusting it
Open a new chat and try a few ordinary questions you'd normally ask — organizing a Saturday, whether to back up photos before a phone switch (our Google Photos backup checklist is a good comparison point here), or comparing two options with limited detail.
If a reply is close but not quite right, tweak one specific phrase rather than rewriting the whole thing. "Use no more than five bullets" beats "be shorter" — it's something ChatGPT can actually act on.
Save the exceptions for the moment they come up
Custom instructions are a default, not a rulebook for every task. Put job-specific details — deadline, audience, budget — directly in your prompt instead. You can always say "for this one, write the longer version," even with a short-answer default set.
For a different repeatable habit, see our guide to using ChatGPT Voice for an action plan — it shows how a few clear constraints turn a loose idea into something usable.
Changing or turning it off
Come back to the same settings page any time your preferences change. Edit, save, then start a fresh chat to see the effect cleanly — an existing conversation may still carry the earlier context. Turn the whole thing off with the same switch if it's not working for you anymore.
If your actual concern is account security rather than tone, that's a separate check — our guide to reviewing ChatGPT active sessions covers unfamiliar devices.
Custom instructions make the first draft better, not automatically correct — read important answers, and check anything time-sensitive against a real source. A handful of durable preferences and one quick test is really all it takes.
Official sources
- OpenAI Help Center: Custom Instructions for ChatGPT
- OpenAI Help Center: ChatGPT release notes