Path to Media privileges

Dear Nicholeen, I hope you're well and looking forward to a nice Thanksgiving with your family.
I would like ask you about how to build a path to train my children to use devices with access to Internet. I have a 14 year old son and he struggles with getting distracted and being sneaky about using the computer sometimes. He uses it for school, but when he gets stuck, let's say writing an essay or solving a Math problem, then he turns to watch a music video or something funny, then he goes into a rabit hole of clicks and scroll.
What are some concrete steps that we can take to build trust again and teach him to be responsible using these devices? He will have to use them when he becomes an adult and we want to make sure we train him the right way, so he use them appropriately and doesn't become bonded to it. Thank you in advance. 🤗