Hi. I'm Brian and I'll try to help.
A Yahoo account does not impact Microsoft products. Do you mean that you used a Yahoo address as the username for a Microsoft account? If that's the case, that account and the Yahoo account have nothing to do with each other except to share the same username.
The birthdate for a Microsoft account is difficult to change. Some countries have laws that require Microsoft to allow the change, but that's not true in the U.S. As far as I know, you won't be able to change it. Nevertheless, I share Microsoft's guidance for this: https://support.microsoft.com/account-billing/837badbc-999e-54d2-2617-d19206b9540a