Alternative way to change login theme. When the KDM Theme Manager does not work.
- Alt + F2, type in kdesu konqueror and hit Run.
- Search your way to this path: /usr/share/apps/kdm/themes.
- Backup the folder Kubuntu by renaming it to for example kubuntubackup.
- Unzip a theme, name the folder Kubuntu and place it in /usr/share/apps/kdm/themes.
Open the KDM Theme Manager and see if the theme is there and selected.

