Find below the steps to update the domain associated with your Global Admin ID and set a new default domain for your Microsoft 365.
1. Add and Verify the New Domain
Before changing the admin ID or setting the default domain, please ensure the new domain is added and verified.
New Domain: mydomain.com
Steps to add/verify the domain:
- Sign in to the Microsoft 365 Admin Center:
https://admin.microsoft.com - Go to Settings → Domains.
- Click Add domain and enter mydomain.com
- Microsoft will provide a TXT DNS record.
- Add this TXT record to your domain registrar’s DNS.
- Return to the admin center and click Verify once DNS propagation completes.
2. Update the Global Admin ID to the New Domain
Current Admin ID: admin@example.onmicrosoft.com
Steps:
- Go to Users → Active Users.
- Choose the Global Admin account.
- Select Manage username and email.
- Update the sign‑in name to the new domain, for example:
admin@mydomain.com - Save your changes.
Note: After the UPN is updated, please use the new admin ID to sign in.
3. Set the New Default Domain
This ensures all new users created in the tenant use the new domain by default.
Steps:
- Go to Settings → Domains.
- Select mydomain.com
- Click Set as default.
