logging into a new computer

Hello.

I guess that during the Microsoft 365 installation, you accepted the default prompt to "Use this account everywhere on your device," which effectively merged your Windows local user profile with your Microsoft Account cloud identity. You should first attempt to log in using the specific password associated with your Microsoft 365 subscription.

And also you should visit account.microsoft.com on a separate device or smartphone to verify that your credentials are correct and to ensure that your account has not been locked due to multiple failed entry attempts.

If you find my answer useful, please mark it as the "Accepted Answer" so other members can find the solution easily. Your help in supporting the community is much appreciated!
Best regards,
Scott

On a brand-new Windows 11 PC with Microsoft 365 just installed, the password prompt at startup is for the Windows sign-in account, not for Microsoft 365 itself.

If none of the passwords being tried work, use the account recovery and reset options associated with that Microsoft account or work/school account:

1. If this is a personal Microsoft account (Outlook.com, Hotmail, etc.):
   • Use the Microsoft account recovery form and related guidance under Account in the “My username and password have stopped working” article to reset the password.
   • See:
     • Help with the Microsoft account recovery form
     • Help with account sign in verification codes
2. If this is a work or school account (Microsoft 365 for business):
   • This is the email account assigned by the organization. The Microsoft 365 license is associated with this account.
   • Contact the organization’s admin or IT helpdesk and ask them to:
     • Confirm the correct username.
     • Reset the password for the work or school account.
3. After the password is reset and confirmed working in a browser (for example by signing in to Microsoft 365 at Office.com as described in the Skype for Business sign-in help article), use the same username and new password to sign in to Windows on the new PC.

If sign-in is still not possible after password reset and verification, contact Microsoft Support or the organization’s IT support using the “I need to talk to a customer support agent” option in the “My username and password have stopped working” article.

References:

• My username and password have stopped working
• I forgot the account I use with Microsoft 365
• Need help signing in to Skype for Business?