How it works:
You can select the settings how you like them but there are lost when you restart/load/create new savegame.
When you have a setting you like click "Save as Default".
Next time you restart/load/create new savegame these settings are loaded...
How to the grey buttons work:
If you have a Game you don't want to use your default settings,
you can stick the current settings to your game. After you saved it, everytime you load the savegame the sticked settings are restored.
If you don't like that anymore, you press unstick and the stick in game is removed. After saveing your savegame it will use the default settings next time you load it as normal savegames
Mostly you don't need the grey buttons, thats why they are grey.

These are mostly for advance gamers who like to play on different games with different enhancegui settings. Like you have one game with only tiny trains, you will stick there settings with a smaller depot as normal / default.
copy from the dev thread