Lifelong Learner

I am 77 years old.  When I discovered Khan Academy I decided to take all my high schoool math classes again to master the parts I didn.'t "get" the frst time around and to be able to move on in more advanced  math areas just because math is like a fun game. I have PD which makes my motor skills slow, espeially key boarding.  When my hands tremor I have to do thngs over but I enjoy working toward a goal.I love the way I can achieve mastery no matter how long it takes.

However, I don't understand how I can have 92% complete in a unit when I got a 100% on the unit test. I thought 100% on the unit test would cause me to level up in all the skills in that unit.  What do I need to do?

I'm trying to achieve 100% mastery.