[Ahriman]

turn the stereo off by pressing the pwr button. then hold the menu button down for a few seconds(i think its the menu button), then a settings screen will pop up that allows you to change all sorts of ****... somwhere in there you can turn sub controls on or off, stock they are set to off. once you turn that on, turn the stereo back on, and there will now be a setting for the subwoofer in the normal "audio" menu.

edit: i see you already messed with the initial settings... the sub controls should be under the "audio" settings now.