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The Guide to Custom Instructions: Stop Repeating Yourself - Digital Compliance Academy

If you find yourself typing "Use UK English" or "Don't waffle" in every prompt, you are doing it wrong. Here is how to set up Custom Instructions in ChatGPT and Claude.

Jon McGreevy December 20, 2025 3 min read
Tutorial Productivity Workflow Setup

Imagine you have a new intern. Every single morning, you have to introduce yourself. “Hi, I’m Jon. I run an AI consultancy. I like direct answers. I hate bullet points.”

And then, at lunch, they forget. So you have to say it again. “Hi, I’m Jon…”

This is what using AI without Custom Instructions feels like. You are onboarding the model from scratch with every new chat. It is exhausting. And it leads to “Drift”—where the AI forgets your style.

What Are Custom Instructions?

Think of Custom Instructions as the Operating System for your AI. It is a set of rules that runs invisibly in the background of every single prompt.

  • You type: “Write a blog post about coffee.”
  • The AI reads: “[USER IS JON. USE UK ENGLISH. BE DIRECT]. Write a blog post about coffee.”

The 2-Part Formula

Whether you use ChatGPT or Claude, the structure is the same. There are two boxes.

Box 1: “Who Are You?” (Context)

This is where you dump your bio. The AI needs to know who it is talking to.

  • Job Title: “I am the Director of an AI Training Agency.”
  • Audience: “I usually write for C-Suite executives and non-technical managers.”
  • Location: “I am based in Liverpool, UK.”
  • Goals: “My goal is to demystify AI technology.”

Box 2: “How Should I Respond?” (Style)

This is where you kill the “AI-isms.”

  • Tone: “Be direct, professional, but conversational. ‘No Bullshit’. Avoid corporate jargon.”
  • Format: “Use frequent headers. Use Markdown bolding for emphasis.”
  • Constraints: “NEVER use the words: ‘delve’, ‘tapestry’, ‘testament’, or ‘landscape’. Ask clarifying questions before starting.”

Platform Specifics

ChatGPT (Settings -> Custom Instructions)

This is global. It applies to every chat. Pro Tip: Create different “Personas” in a word doc and paste them in when you switch modes (e.g., “Coding Mode” vs “Writing Mode”).

Claude (Projects)

Claude does this much better with Projects. You can create a “Project” called “Blog Writing.” Inside that Project, you set the Custom Instructions: “You are an SEO expert editor…” Then you create another Project called “Coding.” Instructions: “You are a Senior Python Dev…”

This allows you to switch “brains” instantly without changing settings.

Our “Golden Template” (Copy Paste This)

Here is the exact instruction set we use at DCA. Feel free to steal it.

Context:

I am Jon McGreevy, founder of DCA. We teach AI literacy to UK businesses. I value clarity, brevity, and practical advice over theory.

Style Guidelines:

  1. Voice: Direct, authoritative, but warm. Use British English (colour, analyse).
  2. Structure: Start with the answer. Don’t say “Here is the answer.” Just give the answer.
  3. Formatting: Use bolding for key terms. Use short paragraphs (1-2 sentences).
  4. No Fluff: Never use moral lectures (“It is important to note…”). Never use conclusion clichés (“In summary…”).
  5. Opinion: Do not be neutral. If a tool is bad, say it is bad.

Summary

Setting up Custom Instructions takes 5 minutes. It will save you 10,000 keystrokes a year.

Stop repeating yourself. Configure your intern once, and let them work.