Dear Psenicna Natalie
Good day!
Thank you for posting to Microsoft Community. We are glad to assist!
Based on your description, I understand you concern with unable to sign in to new Teams account.
May I know whether you have tried to create a new Windows profile and check if there is any difference? New Windows profile will remove all credentials.
May I double confirm whether you have tried to clear the browser cache and cookies?
You may have a try to use InPrivate and Incognito Browsing Mode and check if there is any difference.
In the meanwhile, you can try to reset the Teams app and check if there is any difference. Clear Teams cache - Microsoft Teams | Microsoft Learn
I look forward to your response.
Please note that our initial response may not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution.
Thanks for your precious time and your understanding would be highly appreciated. Have a nice day!
Best regards,
Allen | Community Moderator