Two default browsers?

[Gary Aitken]

I'm a bit embarrassed to even have to ask this...

I have two browsers installed, firefox and chrome.
They both claim to be the default browser, and
neither will allow me to change it.

Can anyone explain to me how this is actually set, reset?
Is it up to the individual browsers to honor their own settings?
There is a
   browser.defaultbrowser.notificationbar
item in firefox's settings, but nothing about the default setting itself,
and no way to turn it off/on.

For chrome, I see no way to make chrome *NOT* the default browser.
~/.config/chromium/Default/Preferences is not a text file, and not easily
editable.

11.4-RELEASE-p3

Thanks for any clues,

Gary