October 06, 2026
You have typed "keep it short" so many times it has become muscle memory. The reply still opens with a paragraph of throat-clearing, still turns a three-line update into a table, still drafts a stiff formal email to a colleague you have known for six years. Custom instructions are the fix. Write the context and the house rules once, and every new chat starts with them already loaded.
Setup takes about ten minutes. Deciding what belongs in those two boxes takes longer, and that is where most setups go wrong: either overloaded with rules, or so vague they change nothing.
Where the setting lives
Open Settings and look for a section called Personalization or Custom instructions. The exact label shifts between the web app, the desktop app and the phone app, so search the settings menu if you cannot spot it straight away.
Inside are two text fields and a toggle for applying your instructions to new chats. The first field asks what should be known about you. The second asks how responses should be shaped. Both take plain sentences rather than code, and you can edit or clear them whenever you like.
Two things are worth knowing before you start. Your instructions apply to conversations you begin after saving them, not to old chats. And they are a default, not a lock: anything you request inside a single message overrides them.
Treat the two boxes as context and behavior
A simple division keeps both fields clean. Box one answers who is asking. Box two answers how the answer should be shaped.
Most disappointing setups fail right here. People put formatting rules in the context box, or fill the behavior box with wishes that do not change a single word of output.
- Weak: "I am a busy professional who values clear communication."
- Useful: "I work in B2B software marketing and write for a technical audience that distrusts hype. Most of what I need is emails, one-page briefs and short social posts."
The second version gives something to work with: a field, an audience, a set of output types. The first is a mood.
Ready-to-paste instruction blocks
Adapt the brackets, delete what does not apply, and keep each box to a handful of lines. Longer is not better. Rules that never come up just dilute the ones that matter.
For work
What to know:
I work in [role and industry] and write mainly for [audience]. My recurring tasks are drafting emails, summarizing meeting notes, outlining proposals and turning rough notes into structured documents. I use [British/American] spelling. I am accountable for whatever I send, so flag assumptions and gaps instead of filling them silently.
How to respond:
Lead with the deliverable, then add reasoning only if it is needed. Default to the shortest complete answer. Plain business English, no filler adjectives. For emails, give me a subject line, a body under 150 words and a clear ask. When I paste messy notes, return decisions, owners and open questions. Ask a clarifying question only when the request is genuinely ambiguous; otherwise make a reasonable assumption and label it.
For study
I am studying [subject] for [course or exam]. I am solid on [topics] and shaky on [topics]. I learn better from worked examples and being questioned than from long explanations.
Tutor me rather than answering for me. Start with a short explanation, then one worked example, then two practice questions of increasing difficulty. Wait for my attempt before showing the solution. When I get something wrong, explain the specific step I missed instead of repeating the whole topic. Define jargon the first time it appears. Skip the praise.
For everyday use
I use this for ordinary things: planning trips, wording awkward messages, choosing between options, brainstorming meals. Give me one recommendation first, then at most two alternatives with a single line each on the trade-offs. Keep formatting light and plans concrete, with steps or timings I can act on.
If you ask about money, health or legal matters, add a line to the second box such as: "For health, legal or financial questions, give general information and remind me to confirm the details with a qualified professional." That keeps answers useful without treating them as advice to act on.
What to leave out
Contradictions are the most common problem, and they stay invisible until you notice replies getting bland and evasive.
- Rules that cancel each other. "Always be thorough" and "keep every answer under 100 words" cannot both win. The model quietly picks one, or satisfies neither.
- Rules that fight the task. "Never use bullet points" is fine until you ask for a comparison of five vendors.
- Sensitive details. Passwords, account numbers, client names you are not free to share. Treat those boxes the way you would treat a shared document.
- Facts with an expiry date. Current project names, this month's deadlines, last quarter's figures. Keep those in the chat where they belong.
- Personality wishlists. "Witty but professional but friendly but not too casual" produces mush. Pick two or three adjectives, chosen the way you would describe a good colleague.
A useful test for any line: does it change what the reply looks like? If you cannot point to a visible difference, cut it.
A five-minute test
Save your instructions, start a fresh chat and run three quick checks.
- Ask for something with an obvious preferred shape, such as summarizing a paragraph of notes, and see whether the format matches what you asked for.
- Ask something slightly vague and notice whether it asks a question or makes a labeled assumption.
- Ask one question from a sensitive area you flagged, and confirm the caution appears.
If a reply ignores a rule, the rule is usually buried or too abstract. Move it to the top of the second box and make it concrete: "under 150 words" beats "concise" every time.
Keep it short enough to follow
Eight to twelve lines across both boxes is a good target. Review once a month and delete anything you have not noticed in four weeks. Instructions you never trigger
Photo: geralt / Pixabay
