Resolved [SOLVED] Starbound.config not being applied when launching via Steam

Where does Steam store Starbound's config data? I manually edited Starbound.config in the Storage folder, but that is only being applied if I launch the game -manually- from win64, instead of using Steam's Play button.

I need Steam's Play button, however, to run Workshop mods. Hence, tell me where Steam is getting / storing Starbound's configuration data to / from.

EDIT: -Finally- got it working... turned out it DOES use that Starbound.config; my manual edits were doing things outside the scope of my machine or Starbound, causing it to shelf the custom Config and make a fresh one.