Outlook
Outlook FAQs
Outlook keeps asking for my password? What do I do?
Occasionally, Microsoft updates will trigger this condition. To fix it, go to Control Panel. Choose Credential Manager > Windows Credentials and remove any entries mentioning MS Office, 365, or Outlook. Then restart Outlook. When you are prompted for credentials once more, enter them. Windows Security may actually prompt more than once. After that, it should not ask again.