i hate to correct such an amazing post, but i think you mean the VU tab. currently this is ONLY on the Front Panel, in the Utility menu as decatur described.* Before tweaking. Go right to the UTILITY page and start strumming a chord until your vol peaks hit that line marked.
* Start tweaking away with just those 3 blocks, Amp, Cab and Reverb.
* Work only with the Input Drive, Input Trim and Master Volume first then B/M/T.
i like everything you said, but i really want to stress this part. after reseting the amp to default values as decatur described, just adjust the Drive and Master volume first. those HAVE to be balanced for the right type of distortion or clean tone you are seeking. use the Level parameter to keep the volume the same as you change these 2 parameters.
only after that, then touch only the Bass Mid and Treb controls. honestly, if you chose the right amp to begin with, that should get you pretty close to the final tone you're seeking. of course, adjust whatever you need to after, but really that little bit should do a lot.
i know people who reset the amp, but then immediately set bass to 2, mid to 7, treb to 4, presence to 7.3, output comp to 1.23, master to 9.32, drive to 10, etc etc etc.... without even playing the guitar!
i've said this soooo many times by now, but i still stand by it - create tones with your EARS and not your eyes. just because the bass parameter is at 5 doesn't mean it is "too much." you need to PLAY and hear exactly what is happening with the bass at 5. you also need to play as close to the volume you will be performing at when setting tones. if that's not possible, then you need to be good at adjusting the global EQ when you get to the gig. a lot of it is just plain physics.