Custom instructions

Custom instructions are standing rules the AI reads before every chat, so you write a preference once instead of in every prompt. In ChatGPT and Microsoft Copilot they're under Settings, then Personalization. In Claude they're the profile instructions in your settings.

Keep them short and about you: how you like answers, and facts that apply to everything you do. These are lines we suggest in trainings:

• "Never use em dashes."
• "Use bullet points for any answer longer than 300 words."
• "Spell out acronyms."
• "I'm based in the UK. Use UK spelling, and UK data for market research."
• "Always respond in English." This fixes a tool that answers in the language of your operating system.
• "When I say I'm starting a project, ask me clarifying questions before you do anything." (More in having it ask you questions.)

Trainees often mix up three features that sound alike:

1. Custom instructions apply to every chat. You write them.
2. Memory is what the AI saves about you over time, either on its own or when you say "remember that our fiscal year starts in February". You can read and delete saved memories in the same settings page.
3. A skill is a recipe for one kind of task, like drafting email in your voice, and loads only when that task comes up.

Set custom instructions up in your first week with a new AI tool, then add a line each time you catch yourself correcting the same thing in a second chat.

Put a rule here only if it should apply everywhere. A rule for one kind of work belongs in a skill, or it leaks into everything else: "use bullet points" is right for a summary and wrong for an email to a customer. Every line also takes up room in every chat's context, so read the list every few months and delete what you no longer need.

Setting up custom instructions, memory, and skills is part of every AI training we run.