I am not able to focus on my studies.

Usually when we experience disturbing thoughts, we may tend to fight, resist or control them. Again, fighting a thought is like fighting a shadow. You can see it, but it's not real. Having said that, fighting a thought or emotion only gives it more power. Say, for instance, when someone asks you not to think of a pink elephant, the first thought that invariably comes to you is that of a pink elephant. Instead, what we can do is, learning to be an observer of such thoughts and emotions( that do not serve your highest good ) and not identify with them or act on them. Right now, your attention span might be, say, 2-3 minutes. Work with it without being hard on yourself to extend it. ' It is only when you release yourself from the prison of your own expectations, will you experience true security '. As you take baby steps in letting go of the need to control this urge to watch YouTube videos, the need to extend the time spent on studies or other pursuits, you'll see that you are able to slowly progress toward accomplishing these goals.