That's weird. And to what resolution do you want to set it?
I've just tried it on my system and it seems to work. Not sure why it doesn't work on yours.
Eventually I'm going to expand the low res mode where you can also choose a resolution. That way the UI stays sharp while the road and stuff becomes pixelated.
I'm afraid not. But you want to change the refresh rate? I believe changing the resolution merely changes the look of the game, not the actual resolution of the screen. So my best bet is to change it in your system settings for the moment.
I'll add an option in the future to actually change the resolution on a system level.
Are you using Windows? Or Mac?
