If you turn AutoSave Off for an individual file the program will remember to keep it off every time you reopen that file. If you switch it back On for an individual file, it will remember to keep in on for that file.

If you want to turn AutoSave off, by default, for all files, go to File > Options > Save and uncheck the box next to AutoSave OneDrive and SharePoint Online files by default on <application>.

The File > Options > Save dialog showing the checkbox to enable or disable autosave

Restart Word (or whichever application you're in) and the change will take effect.

Notes: 

  • If you want AutoSave off by default for all your Office applications, such as PowerPoint and Excel too, you'll need to repeat these steps for each of those programs.

  • If you want individual files to still be AutoSaved you can open those files and manually turn AutoSave back on for those files.