Managing personal Outlook.com account settings, security, and privacy
@Robynn Giese said
I can not remember his Microsoft account password. ... He is a member of my family in Xbox Family but I can't reset his password through that
I am sorry. But for account security purposes, Microsoft treats a child's account the same as an adults. There is no Family settings that can help in this case.
The Account Sign-In Helper will suggest any possible recovery steps.
- In a Private/Incognito browser session, open: https://aka.ms/sign-in-helper
- Scroll down to "Choose how you normally sign in, then enter your details"
- Click "With an email address"
- Enter your email address and click [OK]
But it most cases your only option is the standard Microsoft Account Recovery process:
https://support.microsoft.com/en-us/account-billing/help-with-the-microsoft-account-recovery-form-b19c02d1-a782-dee6-93c3-dc8113b20c42