Is there an easy way to block YouTube for just one child?

[Alex]

Zod said:

If it's Windows 10, set his account up as a child's account and you will get a weekly report of all his activity, including every website visited.

Only if he uses Internet Explorer. Windows Family Safety is pretty good though.

[Efbe]

how old is this child?

The responses here seem to be expecting him to be 15+, however if youtube is his problem and not pron, then I expect he must be under 12.

[GreigM]

Draytek routers have very good and highly configurable firewall rules which can be enabled on a user-by-user basis. It works like a hotel wifi login where upon connecting the user is sent to a landing page where they enter a username/password for their profile and the rules are applied appropriately. Can also do all the logging you want. Expensive and not the simplest thing to configure, but would prevent any future issues with internet access (from within your wifi anyway).