Restore to a Previous Version

1. Click "Revision history"
   
2. Click "OK"
   
3. Click "Revision history"
   
4. Click the "Restore" button for the desired version (in the example below, restoring to Rev. 3)
   

5. Click "Restore". The page will reload and the restoration to the selected data will be executed.
   

6. Make any necessary edits and click "Issue" to confirm the restoration. The latest SOP will be updated.
   

To check which version was restored

Here for more information.