So, I've seen a lot of people having trouble trying to access those options on their account, and I had the same problem myself. However, I've figured out something that may work for some.
Well, in the end it was very simple but...In my case, the parent account was rarely used, only once or twice. The problem was that the new terms and conditions were never accepted, so I even if I had them accepted on my own account, the online safety menu was glitched. So, if it isn't obvious, I simply logged in with my parent account, accepted the new terms and voilà! It worked!
So, that's it! I hope it can be of any help =D