Unfortunately the only way to do this would be to build an entire randomized quiz from scratch. The way that the current templates work simply won't allow you to move backwards, and then forward again.
What's happening now is when you click Back, it is going back to the randomizer, which automatically serves up a new question (and doesn't register that you completed the previous one). If you're using the Randomized Quiz structure, you'll definitely want to lock down navigation. You can remove the Navigation Master
from those quiz pages (and perhaps create a copy that looks similar, but doesn't have navigation buttons).
Or you can use Global Events to disable and enable the navigation buttons. Here's a Video Tutorial
that goes in depth into Global Events.
If you're building a Linear Quiz
, then you can move forward and back, but you lose out on some of the features that the Randomized Quiz Controller gives you (randomization, question pools, Review Mode at the end).