Joseph,
Studying for the PMP exam can be very frustrating -at least it was for me. (I often say here that I'm not a professional Project Manager, but in my business, I must manage projects professionally). For me, it was like learning another language, where the words don't necessarily mean what the words say.
My advice is this: Keep doing the quizzes. LOTS of quizzes. 10-20 questions at a time, focused in a particular area, as the simulator allows. For the questions answered incorrectly, understand the "why" behind the RIGHT answer, then bank that experience for the next similar question. The PMP exam will test on principles, not necessary real-world application or how you would do things in a given scenario.
Good luck!
Harry