Family Sharing
How do a change the birthdate of a child in Family Sharing?
iPhone 6 Plus
How do a change the birthdate of a child in Family Sharing?
iPhone 6 Plus
If it's a child account you can't change it, only iTunes Support can potentially do so : http://www.apple.com/support/itunes/ww (click on your country's flag, the country where you live, and which is therefore the country on the account ; click on Contact Support towards the top right ; click on Get Help under 'Talk To Us’)
Family Sharing