Somebody has a little problem that is about to get a lot bigger. Learning chart symbols is simplicity itself. No interpretation required, no fancy language, just tick the correct box for each squiggle. But it's the price you pay to get licence. Simple learning a five year old could do. As to their relevance for PPL flying that is questionable, but you don't have the luxury of any choice. Aviation law is equally trivial to learn, but does matter. But these two subjects demonstrate your problem. As the professionals have pointed out, the ATPL subjects are a little bit harder but considerablly broader. Some may argue that they are parts that are irrelevant to many aspects of flying but the big thing is if you are struggling now you really shouldn't bother with commercial flying. You won't be able to cope with the exams because you have demonstrated beyond doubt this entry level is above you as you are finding these things difficult. But this does not mean you are stupid. It's just that this job has an entry requirement and you simply can't struggle at this level and expect to make it through.
I wish you the very best in your current career.
PM