You can turn off AutoSave for each file
that you want to only save changes manually using the AutoSave toggle at the top left of the application. Your preference will be remembered next time you open the file again.

If you accidentally make changes to a document, you can easily revert to an earlier version of the document using Version History, which you can find via the Document Titlebar.

Additionally, if you want to turn AutoSave off by default for all cloud files, you can do so through File > Options > Save in each app where you want it disabled. For example, in Word, simply uncheck “AutoSave OneDrive
and SharePoint Online files by default on Word” and then restart for the changes to take effect.

When it’s turned off, you can manually turn on AutoSave by using the AutoSave toggle at the top left of the application window or the Alt + 1 accelerator key.
Please note that AutoSave refers to the new feature for Office 365 subscribers that enables a more seamless experience, including simultaneous real-time editing when working with files stored on the cloud. For files that don’t have AutoSave, such as files on
your local hard drive, or for non-subscribers, there is still AutoRecover, which can help recover changes if you forget to save manually. To learn more, please see
https://support.office.com/en-us/article/What-is-AutoSave-6d6bd723-ebfd-4e40-b5f6-ae6e8088f7a5.