How to configure MangoHud in the Flatpak version of Heroic?

I enabled MangoHud in my game without an issue with the option inside Heroic, but I want to change it's configuration. I tried adding a new MangoHud.conf file in the game folder but it doesn't seem to read that config. Also tried with Goverlay, but that doesn't work either.

So, where can I find the MangoHud.conf file that Heroic uses?

Thank you in advance!