hello;
just did a quick Google search, came up with the following;
not sure how accurate it is.


You are logged onto your computer and Outlook is up and running and boom!
The Outlook password prompt pops up, you enter your credentials and sure
enough,
it pops up again!

Annoying? Yes. Solvable? Yes. This is an easy fix and usually it's just a
matter of removing an Outlook instance in credential manager but first we'll
make sure that you do not have Outlook set to always prompt for password.

First let's make sure that you have Outlook settings set to use Windows
credentials and you do not have Exchange properties checked to always prompt
for
username and password, which I'm sure you don't. If you didn't use to get
the Outlook password prompt before then these settings are probably ok.

To check them click on File > Account Settings > Account Settings > double
click your email account and go to the Security Tab. It should look like
this
with Always prompt for password Unchecked.

Outlook Password Prompt

How To Get Rid of Outlook Password Prompt:

Close Outlook. Open Control Panel > click Credential Manager and look for
any instance of Outlook. Sometimes there can be one or more. Click the drop
down
arrow then click Remove From Vault. Do this for any Outlook instance in
credential manager. Open Outlook and you should not get the Outlook password
prompt
anymore!