In such a broad field as computer science it is impossible to know everything, no matter how good you are. This is why you should always have some resources at hand that help you to grasp new concepts.
This is my personal list of places where i go to to learn new things.
David Zollikofer's website
David is one of the most inspiring people i have ever worked with. I can definitely recommend you to take a look at his website if you are interested in a more in depth and theoretical approach to computer science.
Brilliant is one of the best online learning sites if you are interested in natural sciences and mathematics. Although i was sceptical at first, especially because premium content is not that cheap, i found brilliant.org as one of my go to resources to learn new concepts