I copied the following because this user said it better than me...except he was referencing Reader, not Acrobat Pro. I am an Acrobat Pro DC subscriber. I relied on this feature in Pro 8.1 until recently upgrading.

COPIED: I almost always use adobe ACROBAT in exactly the same way: I mostly read scientific papers and use the comment tools to highlight and/or make notes for myself. This means that almost every time I open up ACROBAT, I will want the comment tools open and it's irritating to have to re-open the comment tools every single time. #FirstWorldProblems I know, but it can't be that hard to add an option to load on startup. Or to just remember the last toolbar state.

Thanks for your consideraton.