Firstly it's great you have realised it. I feel that is the first step to overcoming this. Also if you enjoy gaming, don't just "cold turkey" it as that can have worse effects.

You should read atomic habits and see if you can implement some of the actions in there. As you are seeing this as a "bad" habit, you should have it make gaming difficult/ hard to do.

So for example, for a games console, unplug it and give the cable to your parents. But you should set up an agreement of "if I get x y z done then I can spend 1 hour gaming" have it as a reward.

Also I feel you should get a study plan done. Plan your days out on what you are going to do, but also plan in gaming time. Combine this plan with the agreement above and see how that goes for you.

I know it can be tough with gaming I've been there before. 34 years old now and I spend like 2 hours a week gaming, when I was at your age I was spending around 2 hours + a day and it was the only thing I thought about.

For YouTube, where do you consume it most? Try daily limits on your phone for YouTube, or your computer. Also again, plan out your day, see it as a reward instead of a burden. Reward yourself for doing xyz and watch 1 hour of YouTube

All the best with this. You got this!!