How to change the system document font in Fedora LXDE

[nomnex]

Hi, one of my app GUI prefs says: "use the default system document font (Sans 10)".

Question: I need to change the default system document font from 10 > 13 (some apps relies on the system document font and do not offer a font setting, eg. liferea news reader --> the browser window).

Attachment: default system document font setting (GUI) on Gnome. That's what I want to change on LXDE (this only). How do I do that? Thank you.

Needless to say: LXappearances lets me select a desktop/app font. Nothing about "system wide document font".

[nomnex]

feedback anyone.