i put the wrong birthday in how do i change it

Howdy,

From Update the birth date associated with your Apple ID

On your Apple ID account page

1. Sign in to your Apple ID account page.
2. In the Account section, click Edit.
3. Update your birth date and click Done. If you're changing a birth date for a child, learn what to do. 

Depending on how you created your Apple ID, you might be required to provide additional information or change your Apple ID username from a mobile phone number to an email address.

Note, If you need to change the birth date for someone below age 13, contact Apple Support.*

*Age varies by country or region. If you need to change the birth date for a child, contact Apple Support. 

ivan