Read the Docs
I've watched so many younger developers (in dev experience, not necessarily age) go straight to YouTube to learn new technology. To be honest, a little piece of me dies inside every time I see this.
Go read the docs!
I'll pose one simple question: if you haven't read the docs, how do you know that the video you're watching or tutorial you're reading is teaching you how to do it the right way? Anyone of any skill level can publish a video and tutorial online. The official documentation is guarded like Fort Knox.
Your first resource should always be the actual docs themselves. For JavaScript, that's MDN; for React, that's the React Docs; for Angular... you guessed it... the Angular Docs.
Learning to read and understand the docs is a skill in and of itself. Just like any other skill, the only way you get better at it is by doing it. When you come across concepts you don't understand in the docs, go dig around Google for better understanding.
You're not going to understand 98% of the stuff you read in the docs on the first pass. This is to be expected. But, it'll expose you to all the concepts you're going to encounter, and you'll know where to go find the answer when you come across that problem later. It's a little bit like preparing for an open-book test – if you read all the material beforehand, you can find the answers to the questions in the book much, much quicker during the test saving precious time and allowing you to answer all the questions with great accuracy.
Every time you read the docs, you'll walk away understanding more of it. The goal isn't to understand it in its entirety on any given pass but rather to know where the answer to the problem is. I've personally probably read the React documentation from start to finish a couple of dozen times. You'll learn something new with each pass of reading the docs, or, at the very least, be reminded of a concept that you've forgotten or haven't been utilizing.