Strange log in Accounts

Hi @Herbert Koeneke van Groningen, 

Thank you for reaching out regarding the security concerns involving your device. 

It is my understanding that you have encountered two unrecognized accounts appearing within the Microsoft Teams login interface, an occurrence that followed an unexpected reboot of your laptop several days ago.  

To ensure the integrity of your system and identify the source of these credentials, I recommend performing the following diagnostic steps. 

1/ Firstly, please verify "Access Work or School" settings 

• Microsoft Teams often retrieves account suggestions from the Windows operating system.  
• Please navigate to Settings > Accounts > Access work or school to verify if these unfamiliar identities are registered there. If they appear in this list, they can be disconnected to prevent them from appearing in the Teams login mask. 
• 
• Please disconnect with the strange account if you see in the list. 

2/ Secondly, checking Windows updates. 

Navigate to Settings > Windows Update and select Update history. Within this menu, examine the list of Quality and Driver updates to identify any entries that coincide with the date of the unexpected restart. A successful installation at that time indicates the reboot was a standard procedure to apply system changes, which can often cause the Teams login interface to refresh and display cached accounts. 

Verifying these logs will help clarify whether the system behavior was routine. 

3/ Try clearing stored Windows credentials 

• Unrecognized identities are frequently stored in the system’s credential vault.  
• Access the Control Panel > User Accounts > Credential Manager and select Windows Credentials. Review the list for any entries related to "msteams" or "MicrosoftAccount" that do not belong to you and remove them accordingly. 
•  

4/ Clear the Teams app cache 

• In Settings, select Apps > Installed apps, and then type Microsoft Teams in the search box. 
• Locate the New Microsoft Teams app, select the More options (...) button on the right, and then select Advanced options. 
• In the Reset section, select Reset. 
• Restart Teams to verify that the login mask has been cleared. 

Please refer the article for macOS or classic Teams: Clear the Teams client cache - Microsoft Teams | Microsoft Learn 

Please proceed with these checks at your earliest convenience. Should the accounts reappear or if the strange behavior indicates any suspicious activity, kindly provide those details so I may further check on my side.

In the meantime, I’ve opened a private message. Could you please share a screenshot showing the two accounts you’re seeing so I can review it on my end? Kindly avoid posting it in the public forum due to privacy considerations.

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The two accounts shown on the Microsoft Teams sign-in screen are typically:

1. A work or school account (managed by an organization/IT admin), and
2. A personal Microsoft account (often created for Outlook.com, Xbox, Skype, etc.).

This happens when both account types exist with the same email address or when multiple accounts are connected on the device. It is not caused by a reboot and is not a security issue by itself.

To address or simplify sign-in:

1. Check which account is correct for Teams (work vs. personal)
   • If Teams is for work or school, make sure to choose the work or school account when the prompt appears.
   • If you are seeing the wrong content (for example, only Activity/Community/Chat/Calendar and missing work teams, assignments, or meetings), you are likely signed in with a personal account instead of the work/school account. In that case, sign out and sign back in with the work or school account.
2. If you want to get rid of the “Which account do you want to use?” prompt
   This prompt appears when there are two Microsoft accounts with the same email address:
   • One is a work or school account created by an organization.
   • One is a personal account created by you (or automatically via Xbox/Skype, etc.).
   To stop this prompt, the supported option is to rename the personal Microsoft account:
   • Go to the Manage how you sign in section of the Microsoft account.
   • Add a new email address (alias) or use an existing one.
   • Select Make primary on the alias you want as the main sign-in address.
   After this, the old email will no longer be the primary alias for the personal account, so the overlap with the work/school account is removed and the double-choice prompt should stop.
3. If another organization accidentally created a work/school account with your email
   In rare cases, another organization whose domain matches your personal email domain may have created a work or school account with the same address. In that case, contact that organization and ask them to remove your email from their system so the conflict no longer occurs.
4. If Teams signs in automatically with the wrong account on a work device
   On domain-joined PCs, Teams can automatically sign in with the domain account. To use a different account:
   • Sign out of Teams, then sign back in and enter the credentials for the desired account.
   • If an admin wants to prevent the username from being pre-filled on the Teams sign-in screen, they can set the registry value SkipUpnPrefill under Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\Teams to 1.

If the accounts shown belong to you and you can sign in as expected, no further action is required; the behavior is normal when multiple Microsoft accounts exist.

References:

• Which account do you want to use?
• Troubleshooting sign-in to apps in Microsoft Teams
• Teams will always log into the domain-joined PC account
• Signed in to the wrong account in Microsoft Teams Free