The default version of a document displayed, when you land on the documents page, is the most recent version that has been modified. These versions are created when the save icon is clicked in Edit mode. So, not only are the changes saved, but it also keeps track of a history, allowing you to restore a previous version of the document.
The Version log is accessed by following these steps:
1. Begin by clicking a document
2. Then, click the “More Details” toggle so it switches to “View Details”
On the left hand side you will see four sections: Info, Revisions, Comments, Review
3. Click Revisions
Simply click through any of the versions and it will be displayed on the right hand side
To restore a version of the document so that it's displayed by default on the documents page
1. Click the appropriate version document
2. Click Restore
The Info tab states the information about the document that is selected including the Document Name, Folder is it is, File Type, Size, Date Uploaded and Last modified.