Revising a PDF after reviews and comments

Wondering if people can help with what to do in the final stages of a review. I create a PDF that I'm considering a draft and it needs to be reviewed. I use the "share with others" option and email it to the reviewer with comments allowed. Then the reviewer can open the file and make all the comments and annotations. They click "done" and it alerts me they have completed the review. But...now what? 

As far as I can tell when I open up the file to see their comments, it won't let me edit the file in that screen. So I can't fix the errors they've found. Am I missing something? Or do you have to go back to your original file, the one you saved before you sent it for comments, and do your edits in there and just use the comments version as a guide you refer back to? I'm a little lost on how to get to the final stage of a revised, final version. Many thanks!