Hi @Graeme Tucker (SHIPLEY BUSINESS DEVELOPMENT),
Thank you for posting in this community.
I apologize and empathize that you are having problems. It is true that co-authoring allows multiple users to co-edit a document but sometimes it can make the document messy.
However, this is a default feature in SharePoint Online and we have no way to turn it off for now.
- As long as a user has Edit and above access to a file, they can co-edit the document, so regranting access doesn't solve the problem unless you set the user permissions to below Edit.
- Setting up file checkout is a widely used method to prevent file co-editing. This is because only checked-out users can edit the document, while other users can only read the document.
We are always looking for ways to improve SharePoint, and your feedback and suggestions are very valuable. We suggest that you make further suggestions on this SharePoint Feedback portal regarding the management of the co-authoring function. Your contribution will be highly appreciated.
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