Hi. Recently I have installed kde-full. I've set to sddm. Im greeted with gnome-classic login screen and weird gradient black-white taskbar. How can i change login screen theme, desktop theme or ANYTHING? After right clicking desktop nothing happens, and in the system settings i can't change any sddm or kde settings either. Only desktop background, but not even logging screen background. Please help.

Please include full details about your system, namely what version of which linux distro you are using? Plasma and SDDM versions may also be useful.

You might double-check the permissions on the files in your home directory to make sure they are owned by your user, including in particular the ".config" and ".local" hidden directories and their sub-directories which contain most of the configuration settings.

You said you've "set to sddm", but are greeted with gnome-classic login. I'm not sure what you mean there. Does that mean that SDDM is using a theme resembling gnome-classic? Does that mean that a different DM is being used like GDM or light-dm? Does that mean that SDDM works fine, but when you log in it takes you to a gnome-classic desktop?