I assume, you have the sets of "6 per page" stored in separate questions?
In that case, I recommend to use a random generator to draw 6 out of your 12 questions (sets). This also ensures a rotation of the sets and avoids showing the same sets together in all interviews (which might cause systematic biases).
If that is waht you like, you will need a random generator, and a little PHP code, using
I am not familiar with programming.
No better time to get started :) We will help you here in the online support.