New Leaf wont let me register people as my best friend because of parental control authorization, only i don't have parental controls enabled. I tried enabling them and setting everything to unlocked and that did not work either. I then reset the parental controls and it still does not work
To get it working you need to go to the 3DS System Settings > Parental Controls > Change > Set Restrictions, you will see a list of of programs you can restrict, scroll all the way to the bottom until you see "Child Online Privacy Protection" On my 3DS the little lock next to it was red and locked. Select "Child Online Privacy Protection" and select "Do Not Restrict" then hit OK, agree to the terms and select OK and then Done. Hope this helps.