Go here to change your password: https://register.btinternet.com/cgi-bin/chpasswdsso
If you are satisfied, please kindly provide an OK or Above Rating - so I get paid. Keep in mind you can always come back to this page at any time regarding this question. Thanks!!
Ok Mac or PC?
I suggest you delete the account and then restart the computer and set it up again there could be some corruption.
Which version of Office?
See instructions here:https://support.office.com/en-us/article/Add-or-remove-an-email-account-5a74e3be-7e11-4d9b-99f7-08ec25e9d072#__toc301268941
Thanks let me know