I installed Manjaro KDE. I don't like the default green appearance, so I selected default Breeze theme stuff from every submenu in Look & Feel, Desktop Theme and so on.

Unfortunately, however, this didn't change some of the minor elements that appear throughout KDE, which still show up trimmed in Manjaro's green. For example, suggestions in Firefox's address bar are still highlighted in that green. Sometimes when I right-click, menu items are highlighted in green.

How can I get rid of these things. Maybe even the Manjaro theme entirely, including all the trimmings that seem to be lurking unchanged in unexpected places?

Thanks for your time and help!

Probably you forgot to change gtk2/gtk3 themes to breeze. Thats why you still see green color in firefox.

Forgive my n00bosity, but where might I find those settings?

systemsettings -> Application Style -> Gnome Application Style (GTK) ->

note: you may need to install a package named something like kde-gtk-config[5] and maybe some themes like gtk-metatheme-breeze (not sure what your distro calls them)