How to erase my "Done" history

I want to go over Fundamentals 2 again, but all of the lessons are either marked "100% viewed" or "Done". I want to keep track of where I left off each day, so I want to erase the history that's current there.

I know that I can erase that history if I go to each lesson individually, but I'd like to do all of that at once instead of individually.

How can I get that done?

Thanks.

You can clear your entire history on the history page (button at top of webpage) but the "done" status has to be un-checked individually.