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How to make Gemini, Perplexity and Copilot write in your voice

Published October 22, 2026 · By Your Voice, Installed

Plenty of people use more than one AI tool: Gemini because it's in their Google account, Perplexity for research-heavy writing, Copilot because work runs on Microsoft 365. Each one will write in a generic voice unless you tell it otherwise. The good news is that all three have somewhere to keep standing instructions, and the same voice guide works in each.

Below you'll find how to write that guide once, then where it goes in each tool, based on the companies' own help pages (checked October 2026). Menus change and features depend on your plan, so if something looks different, search the tool's help center for "custom instructions."

First: write one portable voice guide

Your voice guide is a page of specific rules drawn from your own writing. "Short sentences, no exclamation points, never say game-changer" works. "Friendly and professional" doesn't, because every tool interprets it differently.

  1. Gather 3 to 5 pieces of your best writing in different formats.
  2. Ask any AI to analyze them, quoting evidence from your samples for each observation, and to write 10 to 14 Do/Don't rules.
  3. Edit the rules by hand. Remove one-offs, and add your never list, your readers, and a rule to use [placeholders] instead of inventing facts.
  4. Save a full version (around a page) and a short version (about 1,000 to 1,200 characters) for tools with small boxes.

Our voice guide template has a fill-in-the-blanks version.

Gemini: use a Gem (or a skill)

Option A: create a Gem

A Gem is a custom version of Gemini with your own instructions. According to Google's help center:

  1. Go to gemini.google.com and open the sidebar, then choose Gems. If you've never made a Gem, Google says you may find it under Settings and help → Gems.
  2. Choose New Gem and give it a name, like "My Voice."
  3. Paste your full voice guide into the Instructions field. You can optionally add reference files as knowledge.
  4. Save, then open the Gem whenever you want drafts in your voice.

Source: Gemini Apps Help, Gems. Google's tips for Gem instructions are worth a skim too.

Option B: create a Gemini skill

Google has started rolling out skills in the Gemini app. Its help page says you can go to Customize → Skills → Create and upload a SKILL.md file, or a folder or ZIP with SKILL.md in its main folder. The skill name must be lowercase with hyphens, and you need to be 18 or older, signed in, with Keep Activity turned on. This is the same file format Claude uses, so one file can serve both. Our Claude Skill guide shows how to write it.

Source: Gemini Apps Help, Skills.

Heads-up: Google's Workspace admin notes say Gems move under Settings from November 17, 2026, as skills take over, with removal for business accounts no sooner than March 1, 2027. If you're starting fresh, a skill may be the longer-lasting choice. (Source)

Perplexity: use a Project

Perplexity renamed Spaces to Projects. A Project keeps threads, files and instructions together. Per Perplexity's help center:

  1. In the left sidebar, choose Projects → New project. Give it a title, such as "My Voice."
  2. After creating it, open the project's settings and add your voice guide as its instructions. Perplexity lists a limit of 8,000 characters for instructions, which fits a one-page guide comfortably.
  3. Start threads inside the project when you want drafts.

One tip: Perplexity is built around search, so be explicit when you want writing rather than research, such as "Draft a newsletter intro about [topic], using the facts below."

Source: Perplexity Help Center, What are Projects?

Microsoft Copilot

Microsoft 365 Copilot Chat (work or school account)

Microsoft documents custom instructions for Microsoft 365 Copilot Chat:

  1. In Copilot Chat, select … (Settings and more) → Chat settings → Personalization.
  2. Open the Custom instructions tile and choose Edit instructions.
  3. Paste your short version and choose Save instructions.

These apply across your Copilot chats, which is why the short version is a good fit. Your organization's IT admin can turn personalization off. If you don't see the option, that's likely why.

Sources: Microsoft Support, customize how Microsoft 365 Copilot responds and admin controls.

If you use Copilot Notebooks, each notebook can have its own instructions. That's a good place for your full voice guide (Microsoft Support).

Copilot with a personal Microsoft account

Microsoft's consumer documentation covers personalization and memory, but we couldn't find an official custom-instructions setting to point you to. The simple, reliable approach: paste your full voice guide as the first message of a new chat, then ask for what you need. If your app does show a custom instructions option, use your short version there.

Any other AI tool

The same pattern works almost everywhere. Look for a box labeled custom instructions, system prompt, persona or project instructions, and paste your guide there. Use the short version if the box is small, and the start-of-chat method if there's no box at all.

An illustrative example

Here's a made-up short version for a fictional dog trainer:

You write as Sam, a dog trainer. Readers: first-time dog owners, often stressed. Voice: calm, practical, lightly funny. Short sentences. Open with the dog's point of view. Close with one small thing to try today. Never: "fur baby," guilt, promised results, more than one exclamation point. Leave [placeholders] for dates and prices.

That's about 350 characters, small enough for nearly any instruction box.

Keep it consistent

When a draft misses in any tool, update the guide itself, then paste the new version everywhere you use it. Keeping a single source document makes that a two-minute job. And as always, read drafts before publishing, and never put passwords, API keys or confidential client details into instructions.

Want this done for you?

For a guided start on the voice guide, try the free Voice Primer.

Or let us handle it. Your Voice, Installed turns 3 to 5 pieces you've already written into a ready-to-install Claude Skill, ChatGPT setup, portable voice guide, and paste-ready setups for Gemini, Perplexity, Copilot and any tool with an instructions box, plus 3 sample pieces in your voice. Done for you, $39 one time.

Menu names and plan availability in AI tools change often. Steps here follow each company's help pages as of October 2026; check the linked sources if something looks different. Examples are illustrative.