Hi Starke,
This is a known issue in PlanetPress, in that sometimes, you will select a font, but the actual selected font will be another one a few steps above it. It's in fact a very old issue dating back to PlanetPress 4, and it is due to limitations in the way PlanetPress Design is made that it probably won't ever be fixed.
However, there is a simple workaround: select a font a few steps below the one you want. Since it will pick up a font above it, it will end up picking the right font.
Regards,
Raphaël Lalonde-Lefebvre