There’s no way to remember all that information by just watching the tutorials, it’s just too much. What I have always done is watching the tutorials twice. One time as a movie, I just sit back and watch and get an overall view. The I go back from the beginning and this second time is hands on, I go along with the tutorial trying to make things happen, working on Blender trying to do what the teacher is doing, but now I have the easiness of what I’m seeing not being totally foreign concepts. After that is all about practice, practice, practice and as you practice, things start to become second nature and it is at that point that concepts and tool use begin to stick in your head. There’s not even a reason to try and retain it all in your head, it’ll just stick because you use all the tools and go through techniques all the time, at that point it’s not even an effort remember all the information. So practice a lot.