as somebody who studies education I can explain. A lot of teachsrs do suck in explaining yes, let me point that out already. The issue with many teachers is that they do not take the slower or ""dumber"" students into consideration. If you are behind, you are behind, womp womp and fail the class. There is a certain standard that they assume students can follow so that they can already get into more complex tasks very easily. The thing about the math guys on youtube is that they dumb it down to the most basic way they can explain it ever, so simple that anybody could grasp it. I worked with kids with bad grades before, and once you get the hang of it, you know how to dumb it down. Once you get to know the basics, your gears slowly shift and actually adapt and every "bad" explanation your teacher made is slowly making sense. The YT tutorials alone arent helping, it is sort of you finally catching up to the unintelligible bs your teachers were talking about. I cant discredit them completely, because your brain isnt that dumb, the slight grasp of knowledge you took from class is also doing some heavy lifting, yt tutorials alone cant make you suddenly an expert at a topic, its sort of a short term knowledge situation.