IR written Primary/Secondary instrument questions

I'm studying for my written and having an awful time with the
questions dealing with primary/secondary instruments for
pitch/bank/power during various phases of flight. The distinctions
appear to be senseless hair splitting, and I'm getting them mostly
wrong in the practice tests. Some of this is due to my study
materials explaining which is the right answer, but not really *why*.
Is there any way to logically learn this in a way I have a prayer of
remembering, or do I just have to memorize the matrix?

Thanks,
Jeremy