Selecting between original and arranged OST is done in the first main screen option menu before you select which version of the game you play. Your options are All Original, All Arrange, and Normal <?>, which only gives you the remixed tracks for Black Label I think. Once you have selected a game mode the sound menu has is darkened simply to let you know which music will play... kinda lame, but that seems to be the way it works.Dumbass question:
About the included OST - I had my hopes up for a double disc OST similar to the one Futari included, the pack in left me wishing it was the full lineup of tracks, and my favorite remixes were left out as well. Oh well, better luck next time I suppose.