Change yast2 fonts

Hi all i recently upgraded my openSUSE system from 13.1 to 13.2 and it is working great except for one small detail.
The fonts in the gui of yast are really ugly, not unreadable but ugly and only under KDE.
In GNOME they look just fine.

This how it looks under GNOME and after a fresh install in a virtual machine with KDE:
It used to look like that prior to the upgrade under KDE.
This is how it looks now under KDE:

I tried to change the font settings by running KDE systemsettings as root and also with qtconfig as root.
But the settings there are just the same as they are for my personal account.
Nothing seems to change the fonts in yast, and it is only yast that have fonts like this.

I can run kwrite as root with perfectly looking fonts for example.

Even with a new user account yast has this thick fonts.

So now i’m looking for the file that configures the looks of yast.
I allready looked in /etc/YaST2 but couldn’t find anything.

It’s not like i can’t work with yast anymore, but it’s irritating that this small issue messed up my otherwise perfect upgrade :\