I didn't make a mistake. I want to use the Nintendo online app for Splatoon 2, but since I put in my real age (Im 12), I can't use it. My parents are completely fine with me accessing 13+ games and functions. Sorry for not clarifying. Also I'm going to have the help of my mom to call them of course.
They don't need to know the TRUTH, you just need to tell them you must have made a mistake inputting your age. Then you tell them the new birthday. it's nintendo , not high profile like paypal . No worries