Yes. If you just go back to “View All” underneath estimates, there is an edit button to edit the existing estimate. There also is an option to download the scope as a word document. You can just edit from the word document itself.
I do not see any functionality in here that supports storing multiple versions of the same estimate. Right now you could probably save the different versions by downloading each version as a word document and saving it. Hopefully there would be no major discrepancies between the different versions.