You can track and manage information over time with versioning in SharePoint lists and libraries. You can also view and recover previous versions from the item's history. When enabled, new versions are added to an item's history after changes are saved. The number of versions stored and the visibility of draft or minor versions can be modified for each list and library.
Enable and configure versioning in a SharePoint Online list or library
1. Go to the library or list for which you want to enable versioning.
2a. Click Settings (gear icon), and then click Library Settings or List Settings
or
2b. Click Versioning Settings on the settings page.
3. In the Version Settings page, you have the following settings available:
3a. For a Document library:
* Require content approval for submitted items.
* Create a version each time you edit a file in this document library using either major versions only, or major and minor versions.
* Limit the number of versions and drafts to retain.
* Set who can see draft items.
* Require documents to be checked before they can be edited.
3b. For a List:
* Require content approval for submitted items.
* Create a version each time you edit an item in the list.
* Limit the number of versions and drafts to retain.
* Set who can see draft items in the list.
5. Set as needed and Click OK.
Disable versioning in a SharePoint Online list or library
Do the same steps for enabling, but click No versioning on the Version Settings page. You can also check No for Require content approval.
View, restore, or delete an earlier version in a SharePoint Online list or library
1. Go to the list or library with the item or document for which you want to view history.
2. Click the ellipsis (...) next to the item for which you want to view history.
3. Click Version History.
* If you don't see Version History, click More, and then click Version History.
4. In the Version History dialog box, hover your mouse over the date link on an earlier version and click the down arrow to show the menu.
5. In the menu, you can do the following.
* View the current document. This will bring up a dialog where you can edit, restore, or delete, as well as see the current approval status.
* Restore the document. This option displays a dialog asking if you want to make it the currently approved document. It will add it as a new version.
* Delete the document. This option displays a dialog asking if you're sure you want to send the item to the Recycle Bin.
* Reject this version. This only shows up on approved documents, rather than Delete.
6. When you're done, click the X in the upper right corner.