The OP seems to be having a particular problem with book learning and I share that. How to overcome that depends to a large extent on our temperament. For example, my wife has a photographic memory and can visualize a page in her mind. I think we probably all have some ability to do that and this means it is important to always use the same written material. For me though, that is not enough and the only way I can reliably remember what I have read is to write it down, time and time again. I try to imagine that I am trying to explain it to another person. It uses a hell of a lot of paper but its worth it. This particularly applies to information which you need to pass the exams but are unlikely to need again.
I was doing this just before my Air Law exam while on a BA flight and it turned out that one of the cabin crew had a PPL and he started to help me.