When I go to Mail.app --> Preferences --> Accounts Tab --> (affected e-mail account)... The listing under Account Information does not have an opportunity to change the password. (It lists Description, Alias, email address, Full Name, Incoming Mail Server grayed out, Username grayed out, Outgoing Mail Server SMTP and TLS Certificate) Under the other sub-tabs (Mailbox Behaviors and Advanced) also no opportunity to update or enter a password.
If I go into Mail.app--> Accounts --> (affected e-mail account)... I see only the opportunity to look at "Details" where there is also no choice to update or add a password.
If I go into System Preferences --> Accounts --> (affected e-mail account)... I see the same as listed above... "Details" where there is no choice to update or add a password.
I did find a solution... which is completely terrible for the easiest computer to use... a Mac... which was to delete the mail account, and add it back in, but I then had to add it back to my three Macs and on my two iOS devices. It seems like Apple should have a better solution than that! (Like a prompt when checking mail on that account to prompt to enter a (new or updated) password.)
Thanks for taking the time on this. You do not need to continue on it, as I found an awkward solution... but wondered if I was missing a solution that was simple and intuitive somehow. Again, thank you.