Change Birthday

Hello, I have a really simple problem however it’s something that I have to do in order to be able to download any apps. So I accidentally set my birthday to an absurdly incorrect year - 12/23/2413. The peculiar thing is when ever I go into my apple account setting on my phone and go to change it to my actual birthdate;(05/19/1997) it actually just says “enter a valid birthdate” then not update. Excuse me what?! Really not sure what to do and I’m equally confused how it set my birthdate to something that rediculous in the first place. This is an exceedingly inconvenient situation that I want/need resolved right now.