I may have misread the post - I was thinking knobs .... here's how I use them
1) style/song vol .........2) upper vol
1) arr mute A ..............2) arr/kb bal
1) Vox harm vol ..........2) lead Vox FX (on/off)

As for the 6 (8 on Big Daddy) buttons ...
1-4 are the OTS sounds - 5 is split point (to change trigger from Upp to Low),
and 6 is Vox harm on/off (this is also on a F/S)

My soft buttons (in the screen, at the bottom) are set to:
Transpose (to change audio files) - Chord looper (for loaded patterns), then
Live control (to reassign) - Voice Part
Lyrics - Tempo