1. Click Upload New Version from any of these locations:The file detail pageThe file previewerThe Files page, via the actions arrow for the fileOn a file in a feed, via the More Actions arrow (available in Salesforce Classic only)
2. The file detail page
3. The file previewer
4. The Files page, via the actions arrow for the file
5. On a file in a feed, via the More Actions arrow (available in Salesforce Classic only)
6. Click Choose File, and select a file from your computer.At this point you have the option to enter a note about what changed in the What Changed? field. This information is shown on the Version History list.
7. Click Upload New Version (Salesforce Classic) orStart Upload (Lightning Experience).