How to reset system variables in Quiz, it possible?

This variables to show in the end (and loaded into the system of distance learning).

How to reset this variables? It possible? (I create and zero my own variables, but when I pass through the test, the system variables begin to be summed up with each attempt).

I need this to assign an action to my own button to start anew (I use the standard restart button, but I also need my own).