So, you're working with Copilot in Word, on a document saved in SharePoint, and you ask it to make some updates. It does, and you move on. We've all heard that Copilot respects your permissions and won't surface anything you don't already have access to. Good. Then you open the version history of the document and see your own name against the change. Nothing says Copilot wrote it. Why? Because Copilot is you.
That's worth thinking about before you use Copilot on documents other people rely on.
What I Tested
I used Copilot in Word and Copilot in SharePoint to update a document stored in a document library.
Copilot in Word Edits the File and Records It as You
- The change appeared in version history under my name, with nothing to show Copilot was involved.
- It behaved the same in the desktop app and Word on the web.
- I gave Copilot two prompts and ended up with one new version, not two. You can't step back through each prompt and review them one at a time. That's ok if there are lots of changes to do in one pass. Good.
Copilot in SharePoint Makes a Copy
When I asked Copilot in SharePoint to update a document, the replace operation was declined. Instead of overwriting the original, Copilot stopped, made a copy of the document and made the changes there. The copy has a "1" added to the file name, and it also shows me as the author.
That's a sensible outcome, since the original is untouched. It also means you now have two files, and it's easy to lose track of which is which. But then you're thinking, wait, why did I do that?
What You Won't See
I couldn't find any Copilot marker in either case: no watermark, no label in version history, nothing in the file details. The file's properties and the "Modified By" column show the same thing as version history: my name, nothing else. As far as the file is concerned, I did it. And, of course, I did. So, I'm Copilot and Copilot is me. That makes sense.
Even Copilot Can't Tell
I asked Copilot whether it could tell who last updated the document. It told me the last modified metadata showed my name. That makes sense: it can only read what the file records, and the file records the person who made the request. If you're relying on Copilot, or anyone else, to tell you which edits were AI-written, it won't be able to.
Why This Matters
- Version history is often used to answer the question "who changed this?" With Copilot, the answer is the person who asked, whether or not they read the result.
- You can't tell from the history which edits were written by a person. Well, not really.
- If someone approves a document because "Sam, no wait, Cam, updated it", they may not realise Sam never read the AI-written changes.
A Simple Routine for Checking Copilot's Work
- Read the result. Skim all of it, not only the part you asked about.
- Check what else changed. Open version history, open the previous version, and compare it against the new one.
- Compare properly. Version history doesn't give you a direct comparison of two versions. Save the earlier version as a separate copy, then use Word's Review → Compare to see exactly what changed between the two.
- Restore if it's wrong. Open version history, choose the version before Copilot, and select Restore. Everything after it stays in the history, so nothing is lost.
- Keep a note. Add a line to the document's change log, or to a version comment, such as "Updated with Copilot, reviewed by [name - OK it was me!]". Whether you can add a comment when a version saves depends on your library's version history settings. Check with your SharePoint admin if you don't see the option.
For Teams
- Agree that Copilot edits must be read before the file is shared.
- Decide how you'll mark Copilot-assisted changes: a line in the change log, or a naming convention for copies, or comments.
- For important documents, turn on version history limits and consider requiring check-out or approval, so a person always signs off.
- Admins may be able to see in Microsoft Purview audit logs that a person used Copilot on a document, but this is separate from version history. It doesn't mark individual changes as AI-written, and readers can't see it. We'll get that...
Common Questions
Can I tell what Copilot changed?
Not from version history. Compare the old and new versions yourself.
Can I undo one Copilot prompt?
In my testing, two prompts produced one version, so you can only go back to before both. Save or check your work between prompts if you need each change on its own.
Will Copilot overwrite my original?
In Word it edits in place, but the old version is kept in version history. In SharePoint, my replace was declined and it saved a copy instead.