Copilot Cowork: Personal Instructions vs Skills

If you’re using Copilot Co-work, it’s easy to confuse personal instructions and skills. Both shape what Co-work produces, but they work in very different ways. Instructions apply across every Co-work interaction, while skills only activate when they are triggered by your prompt or manually selected. In this video, Devin Knight breaks down when to use Copilot Co-work instructions versus skills, how each one is created, and why both can make your AI outputs more consistent and useful. You’ll see how personal instructions can define your preferred writing style, formatting, tone, and default behavior across all Co-work responses. Then, you’ll learn how custom skills can support more specific scenarios, like following a brand guide, generating diagrams, or explaining technical concepts with everyday analogies. Devin also walks through creating personal instructions from an “about me” markdown file, building a custom “Analogy Machine” skill, reviewing the skill file in OneDrive, understanding the YAML and markdown structure, and manually calling a skill with the forward slash menu when Co-work does not trigger it automatically. If you want Co-work to produce better, more consistent, and more context-aware results, this tutorial will help you understand exactly when to use instructions and when to use skills. https://ruben.substack.com/p/youre-ju... Create a custom skill called Analogy Machine. Its purpose is to explain a hard technical concept by anchoring it to a familiar everyday situation, so a non-expert gets it on the first pass. It should trigger automatically whenever I'm drafting or revising an email or training content (slides, scripts, walkthroughs, handouts) that introduces a technical concept, term, acronym, or process — even if I don't use the word "analogy." It should not trigger on formal proposals, SOWs, or contracts, since those need precise definitions rather than imagery. Analogies should come only from everyday household and office life — kitchens, inboxes, thermostats, keys, calendars, grocery stores, and the like — using this test: would a brand-new hire and a 30-year veteran both instantly recognize it? For output, it should produce exactly one analogy, fully developed rather than a list of options, mapping two to four of the concept's moving parts to the familiar scene so the analogy actually explains rather than just decorates. It should end with one sentence naming where the analogy breaks down, and keep the whole thing to a short paragraph or two of clean prose I can drop straight into my draft. Include two or three worked examples so the skill has a clear pattern to imitate. 00:00 Instructions vs skills in Copilot Co-work 00:48 What instructions are and how they shape every response 01:57 How to create Co-work instructions from a prompt 02:19 What skills are and when they trigger 03:02 When to use instructions vs skills 04:12 Custom instructions in Copilot Chat vs Co-work 04:57 Create personal instructions inside Co-work 05:38 Build an “about me” writing style file 07:20 Use a markdown file to generate instructions 09:24 Confirm instructions saved and synced to OneDrive 10:06 Skills are triggered, instructions are always active 10:27 Find and manually call skills with forward slash 11:05 Create a new custom skill 11:34 Build the Analogy Machine skill 13:08 Skill Management creates and audits the skill 14:53 Find the skill.md file in OneDrive 15:42 Review YAML triggers and markdown skill content 16:36 View the generated Copilot instructions file 17:15 Test the skill with a PowerPoint prompt 18:40 Manually apply the Analogy Machine skill 20:03 Integrate the analogy into the deck 21:10 Final recap: when to use instructions and skills