I installed a subwoofer kit today and my head unit Alpine UTE-72BT won't change the subwoofer level. Subwoofer is turned on from the settings, and the subwoofer is always on maximum, doesn't matter what number setting is on (0-15). The subwoofer and amplifier is from an old car of mine and I can confirm that the settings are 100% correct and worked well on the head unit of another car.