No problem! I can completely understand that, personally I would say there's a couple of ways of making it more manageable. TL;DR on the last paragraph again haha, sorry! For more info feel free to read through
Firstly, you could look through the specs for each science (they're on AQA's website). I found it took me about half an hour to skim read them, but obviously this may vary for you. Then, whenever you find a topic that you think you've forgotten some of it (e.g. you may read about the Generator effect and go 'what does that do?'), note that down, and then just search up that specific video.
Secondly, you could do a past paper. I'd recommend this anyway, but sometimes it's easy to go through a spec and think you've forgotten something, when in fact you haven't, and exam conditions can help you remember (or forget haha, but sometimes you surprise yourself). Then, look at the questions which you didn't get any marks for/as many marks as you'd like, and again note down their topics and watch the corresponding video.
That method does take more time, and also some topics can be missed in papers, so it's not fully accurate, but still worth it for pinpointing exact topics you struggle with.
I like the latter (and a mix) just because it really gives you proof that you can do certain topics, otherwise it's easy to doubt yourself. Again, personal preference though!
To summarise that, you can use past papers/specifications to make a list of any topics you really struggle with/think you do, and then you can search them up to minimize the confusion of trying to focus your revision. It's easy to be daunted by the pages upon pages of the spec, or the hundreds of videos, but you'll find you will probably only need to revise a few, as the rest will already be cemented in your mind. Hopefully this makes sense? Best of luck once more, let me know if you have any other questions!
P.S. another reason I like the latter option is because papers are excellent anyway for revision, and cementing knowledge, so it's a double whammy. Though it takes longer than the former, it's often else boring too