I have tried this and it works you have to do it for all the different files you want to change the Fonts in.
Just to confirm, yes you need to do what Pavloven says, you need to edit the font type/size on all the file options :/ .
OffTopic: I personally "hate" white backgrounds in code editors, it could be nice that Creator come with some editable skins on the next versions.
Good point, Carlos. Setting all the file's fonts separately or having yellow characters on black background (PASCAL) would be nice.
But here is the developer forum, we cannot change anything. I would suggest you to create a support case so that Cypress knews about this demand.
Thank you all for your help! Yes indeed I was missing that field somehow. It works fine.