I hope you didn't mean it about the "last" version.

I love that you added the credits option. Makes it fit right in with the Arcade cabinet games.
There are a few VERY minor things that would improve usability... especially for guests who don't use the machines every day:
In my priority order of implementation:
Buzz in button should be able to be different from the player start button. Player start buttons are (often) not located near the player's joystick / other buttons on an arcade panel.
Buzz in and select button should be able to be the same. This would then be a true one stick / one button per player game. Hit the button to buzz in... Move to highlight answer... press button again to enter selection.
To make the coin / credit feature useful on most cabinets, you need to be able to specify multiple (up to 4 different) buttons that will add a credit. Most folks who have multiple coin slots have each slot mapped to a different key-press. (i.e. 1=player 1 credit, 2=player 2 credit, 3=player 3 credit, f=player 4 credit). You would just want to add a credit regardless of WHICH credit button was entered.
Allow the order of the players across the top to be changed. My 4 player panel actually has player 3 at the far left, player 1 left center, player 2 right center, player 4 far right. The player start buttons are in that order... so that's where folks will expect to stand. It would be nice if the player scores could be ordered the same way.
It would be nice in the skin options if the "hi light field" color during joystick selection could be a different color for each player.
This is an AWESOME piece of software; a great credit to you that you're down to "user interface" clean-ups and improvements in such a short time.