Thanks for the feedback.
I hadn't realised the stage select wasn't going back to the last stage you played when you exit the game, honestly (this is definitely working on something else I've been working on recently...). Not allowing you to Next Stage from something you've already cleared is also a good point. I'll take a look at it when I get a few minutes spare. I should probably update this to put in an icon for the new list view anyway.
The S, A, A1/2 was something I patched in after the fact to address some other comments so didn't really put much of a nice UI on it. It changes the crank behaviour in game - A setting means that 1 rotation of the crank rotates the turntable all the way around, whereas A 1/2 means one crank rotation moves the turnable half the way around. S is the standard setting I playtested the game around.