I accidentally put my dob under 13 and i want to change it

Are you younger than 13? If no, see this --> Update the birthday associated with an Apple Account - Apple Support

But I'm guessing you're part of either parental controls or a family share plan, and in that case you need the family organizers help.

See this

To change a birthday to any age below 13, the account must be a member of a Family Sharing group, and the Family Sharing organizer must approve the change.

If you convert an Apple Account to a child account