Well if I click at "Elegant glöd" its change all things to "Elegant glöd" in färgschema, panelbakgrund, kick off and the other things in the left menu to at once.
Same if I click at "Oxygen" all things changes to oxygen.
You are selecting a theme for editing, you are not telling the desktop to use a specific theme.
So I need not to do any adjustments there, on the left side below:
But when I want to save it and click on the "verkställ" button it not working.
It's working, if you really do edit a theme.
did you try it?