Auto save is not working.

Save and reopen the document directly through Word’s OneDrive location, because AutoSave does not activate for files opened from a local Windows path.

Turn AutoSave on

1. In Word, select File → Save As.
2. Select your OneDrive personal, work, or school account.
   • If OneDrive is missing, select Sign in or Add a Place.
3. Choose a folder, enter a filename, and select Save.
4. Close the document.
5. Reopen it using Word → File → Open → OneDrive—not File Explorer, the taskbar’s recent-files list, or a local path.
6. Turn on the AutoSave switch in Word’s upper-left corner.

Microsoft documents that AutoSave requires an active Microsoft 365 subscription and a file stored in OneDrive or SharePoint. Opening a local copy—even one under a path beginning with C:\Users\—can leave AutoSave disabled. ^1^

If the switch remains off

Check these items in order:

1. Go to File → Options → Save.
2. Select AutoSave OneDrive and SharePoint Online files by default in Word, if it is cleared.
3. Restart Word and reopen the document through File → Open → OneDrive.
4. Confirm that:
   • Your Microsoft 365 subscription is active.
   • The document uses a current format such as .docx, not the older .doc format.
   • OneDrive synchronization is not paused.
   • The document is not embedded inside another Office file.

AutoSave works only for cloud-hosted files; local files use AutoRecover instead. AutoRecover settings are available under File → Options → Save, but AutoRecover provides crash recovery rather than continuously saving the working document to OneDrive. ^1^

If this still affects every .docx file opened directly from OneDrive, check File → Account → Product Information and confirm that Word reports an active Microsoft 365 subscription rather than a perpetual Office edition.

References

1. Turn on autosave in Microsoft 365 apps | Microsoft Support