You can always take some quick notes and keep them to the side. When you go into a boss fight that you've forgotten, you can briefly skim through a few things to jog your memory. Should only take a few seconds, honestly.

Just an idea at the top of my head to help. c:

Personally, I just roll with it and I'll remember what to do as the fight progresses, but that's just how my brain works. I'm too lazy to take any notes, lol.