I had the same problem. I got around it by setting up the "initial" profile as the kids account, and i used one of the new profiles as my (adult) account. The initial account retained all of the kids suggestions etc, but the new profile i setup for me had no history or suggestions so was as new. It's not perfect, but at least the kids retain all their previous suggestions and history and i get to start with a clean slate!
That's actually not a bad idea. And on new devices it should default to the kid-friendly option automagically. Nice one.