[solved] changing interface fonts on ubuntu 7.10

I installed 0.5 package on ubuntu 7.10 on a notebook with a quite small screen, and wanted to change the interface fonts, as the default ones are very big and looks ugly.
I changed it in qtconfig, it works with k3B, kino, but not kdenlive.
Is there another way to force it ? in kdenliverc file ? Or are they fixed at compilation time ? bug ?

edit : with kcontrol it works fine. fonts and appearance can be changed easily.