how to update my age on the account?

from, https://helpx.adobe.com/photoshop/using/generative-fill.html

Why is the Generative Fill button greyed out if I'm over 18?

If you find that Generative Fill is greyed out for you and you're over the age of 18, it is possible that you may not have a valid Date of Birth associated with your Adobe ID account. To update your Date of Birth, you can do either of the following:

Sign out and sign back in to both the Creative Cloud Desktop app and the Photoshop (beta) app

Log into Behance with your Adobe ID and enter your Date of Birth.

If you sign in using social sign-in (Apple, Google, and Facebook), ensure that your date of birth in that account is set to public instead of private.

Once your Date of Birth is up to date, relaunch the Photoshop (beta) app to enable Generative Fill.