If steam says it can't find DwarfCorp.exe...

...Open your steam library folder (for me that's C:/program files (x86)/Steam/Steamapps/common/ ) and find the DwarfCorp folder. Inside it, you want DCMono.exe

I have changed the settings in steam but - yeah, I have no idea how long it takes for them to kick in!

This is NOT a game update. This is the June 2021 version of the game ported to monogame, which allows it to run on a lot of hardware that the previous XNA version did not.