This article shows what to do if Outlook keeps asking for username and password. The most common cause is having old credentials stored in the credential manager.
Clearing the credential manager:
Open the Control Panel from the start menu.
If using Windows 8, right-click on the start button and select Control Panel.
- Select small icons from the View by drop-down in the upper right.
- Select Credential Manager.
- Select Windows Credentials.
- Locate the Outlook credentials under the Generic Credentials header.
They will look like MS.Outlook:firstname.lastname@example.org, or MicrosoftOffice15_Data:SSPI:email@example.com.
- Click the drop-down arrow next to the credential.
- Select Remove.
- Close and re-open Outlook.
- Enter your credentials when prompted, using your email address as the username.
- Ensure that you check Remember my credentials.