Hi Ken,
Using the playbar is not the way to go, I even will always turn off the playbar for quiz slides.
You have to allow multiple attempts on Quiz level. See screenshot: here I allow 3 attempts and activated the Retake button. This retake button is resetting the quiz but it appears on the Score slide.

This is why I talked in my previous answer about the 2 levels. The attempts set for a Question slide (in its Quiz Properties panel) will indeed have to be exhausted before leaving that question slide. With the attempts on Quiz level, you'll have the work flow you described. And really, turn of the playbar by assigning the value 0 to the system variable cpCmndShowPlaybar on entering the first question slide, and assign the value 1 on entering the first slide after the score slide. Because going back or rewinding with the playbar will not reset the quiz.
Lilybiri