You have to find mod.config and using notepad/wordpad/notepad++ or similar program change
Which is at the bottom of file into the button you want (for example G)
In this case don't forget to change "toss a glowstick" in the fortresscraft launcher to something other (If you don't then you will throw 2 glowsticks, one that costs energy and one that doesn't)



Location of mod.config:

• On windows:
  Default location:
  C:\Program Files\Steam\SteamApps\workshop\content\254200\1443242654\mod.config
  
  If you have changed steam installation location or choosed custom install location for fortresscraft evolved then it is:
  *custom location*\Steam\SteamApps\workshop\content\254200\1443242654\mod.config
  
  
  
• On mac/linux: No idea, I don't have those systems.