Oh, you can do the same thing I told you for WMR, but in this case, the path is "C:\Users\<your username>\AppData\Roaming\Godot\app_userdata\Simple Marble Race", then open "settings.cfg" and change "coins" value to the amount you want :)
How would i do this on mac
Try this path: ~/Library/Application Support/Godot/app_userdata/Simple Marble Race
It worked, you rock.
