Hello,
Welcome to Microsoft Community.
As per your query you are unable to change your Date of Birth in your account as you don't have parental control, so you have to firstly change your organizer account and for that you have to follow given steps:
- Visit the Family Safety portal Go to family.microsoft.com and sign in with the current organizer (parent) account.
- Add a new organizer (parent)
- Select “Add a family member”
- Choose “Organizer” and enter the email address of the new parent account.
- The invited person must accept the invitation via email.
- Remove the old organizer (if needed) Once the new organizer is added, the old one can leave the family group or be removed by another organizer.
After this you can give permission to that account to change your Date of Birth.
For Child Accounts (or if Microsoft thinks you're underage)
If your account is flagged as a child’s, you’ll need a parent or organizer account to make changes:
Sign in to family.microsoft.com with the organizer account.
Select the child’s profile and choose “Manage my child’s profile info.”
Click Edit this child’s personal info, then update the DOB.
Thank you and have a great day.