Default font does not stick

Hi there.
I would like to change the default font in the main Preference window under General - Appearence.
After my confirmation with the OK button, nothing changes. When I open the Prefrences again it's again set to the first font available.
Is it just me? Am I doing something wrong? Or is it a bug?
I'm on a Mac. Tried with 3 different computers with MacOS 10.13.6, macOS 10.15.7 and the new macOS 11. All the same.

Hi,
When you change the font you need to restart qtVlm, then it should be OK.

thanks! that was it. wasn't really obvious to me.