How to study?

Until now, I've never learnt how to study because I didn't have to - I remembered everything from classes + did homework and that was enough for good grades. Now I'm in uni, it's my first year, I have so many things from my textbook to study by myself (here it's rare for the professor put on the exam things we didn't talk about during lectures) and I can't focus. I have tried to do it in complete silence, I've tried with some calm music, classical music but I just can't focus. I don't wanna rely on YouTube videos (which would've been better because I prefer to study from hearing instead of reading), because I once did and it turned out to not be correct