just right click the account in the left pane and select settings.

Thanks, Matt, but I honestly do not understand your suggestion. When I right-click the account (or anything else) in the left pane of the Account Settings window, no menu is displayed.

Serious question here Is your mouse broken?

There have been right click context menus on Thunderbird folder pane always, and I am unaware of an add-on ot theme that accidentally prevents that from working.

Try restarting Thunderbird with the restart with add-ons disabled on the tools menu and see if menus appear.

Serious misunderstanding here. We are talking about the Account Settings window (Tools > Account Settings) and not about the main Thunderbird window. Thanks.

Yes and changing the way you get there will get the result you want. Otherwise your stuck with what you have.