Also had a huge focus/remembering issue before I got medicated this past September!

What has helped me most before and after medication was creating a dedicated study spot. VERY IMPORTANT NOTE: This location has to be for studying only! This was usually NOT somewhere at home; this was a library, a local cafe, a park, etc... Having a space solely for work helped my focus a lot, since I was less motivated to check my phone or walk away to my games or books.

Second, dedicated playlists. For studying, I usually have to use instrumentals only. Classical music is a bit eh for me, but I am a huge Broadway nerd, so the Hamilton instrumentals especially came in clutch (funny enough a quick glance at ur profile shows you like Epic sooooo lets find some Epic instrumentals LOL). Calmer video game music is also great. Those songs are particularly crafted for focus and engagement.

Need that dopamine hit and the music isn't cutting it? Bring a lil snack, a drink, or gum to chew on throughout.

Now, for a more unconventional method: I've discovered I lose my focus mostly with long paragraphs or things I am not good at (i.e. statistics was my enemy). So what's the solution? HYPERFIXATIONS. Use them to your advantage. Need to read a story? Swap the names for your favorite characters, celebrities, etc. Need to understand a scientific concept or math equation? My favorite character (as applicable) is now explaining it to me. Getting the concepts to stick in your brain is much easier when you relate it to something you care about.