SharePoint keeps track of changes and updates of files in your library. You can see the changes that were made and when.
SharePoint also allows you to revert back to previous versions of documents. Please read our article about SharePoint versions.
Step 1: Navigate and open the Document Library that contains the applicable file.
Step 2: Click on the Open the Details Pane icon.
Step 3: Here you can view the Activity section to see all the changes.
Note: When a file is selected, you may see a preview and file properties in the details pane before the file activity. When more than one file is selected, you can edit the properties of the selected files. When no files are selected, you will see activity on the library.