The way the APP seems to work, is that the questions stay the same until you are getting most of them right consistently, then it starts to add new ones. Just keep doing it over again, and the more questions you get right, the more you will see new questions comming up.
At some point, even though you are getting all the questions right, no more new ones will come up. Then yoiu have covered all the questions on that subject.
MJ
