Whether you need to bring back a prior version of an estimate after making changes internally or you want to show a customer an earlier version of their estimate, you can access past estimates by scrolling to the bottom of the estimates tab to the section entitled Estimate Versions.
Here, you can either download the previous Estimate PDF or you can click the three horizontal dots to the right of the record and select Restore.
Note: if you are still actively editing an estimate, you'll need to scroll up to the More dropdown within the estimate tab and select either Mark as Approved, Mark as Rejected, or Void in order to restore to a previous version.