I have played multiple different instruments for 15+ years since I was young, and many teachers have attempted to teach me music theory.
However to me it just simply does not "make sense."
Aside from it being hard for me, I just do not understand why a lot of the concepts exist in the first place.
For instance, (note: I am probably writing this wrong since English is not my native language) I don't understand why the name of the notes change based on which scale the piece was written in. In fact, I don't understand why a scale even exists because why are we shifting everything to different names? Why is the sound that this one key on the piano makes called multiple different names when it is still making the same sound?
For a long time I thought I was just genuinely too stupid, but I'm trying to learn it again because I got interested in songmaking and now I'm wondering if my mindset was wrong the whole time. Should I just try to treat is as a set of rules that just... exist and cannot be changed instead of trying to understand why they exist?
Edit: So the thing about "changing names," i think i was referring to solfèges. So I was talking about how in C Major Do is C but in D Major Do is D. Here i just realized it's also the words in my native language that made it more confusing to me, it would be too long to explain but the English terms are less confusing