Choose and edit voices
When you touch the Voices button in the top of the main view, you will be presented with a list of voices that you can select from. There are the 128 single GM voices and a number of multivoices with harmonies and layered instruments. When you select a voice it will be activated and you return to the main view. If you touch the Edit button instead, the voice edit view will appear.
On the left side you can select which voice to Edit. If you want to create a new voice then select one of the voices names "ZZZ empty" at the end of the list and give it a new name. On the right side you see the properties of one of the 4 voice layers. You can switch between the layers with the tabs at the bottom.
Voice layer 1 is always assigned to the right hand, it will sound if you play melody on the right side of the keyboard. It can have added harmonies following the chords.
The voice layers 2 thru 4 can be assigned to right hand, left hand or bass/split. The left hand is played with the keys in the chord area, by default the left hand is muted so that this voice layer won't play. The bass/split is played by notes on the channel defined as the bass channel in Settings/Keyboard or is in the range defined by keyboard split in Settings/Keyboard.
In the patch popup list you can select one of the 128 GM instruments. If your synthesizer has multiple banks with instruments, then you can specify the bank with the msb and lsb (if you only know the banknumbers: the formula is 128*msb + lsb = banknumber).
The instrument may be assigned an octave higher or lower and you can specify volume, reverb, chorus, modulation and pan (if your synthesizer responds to these).
The channel can be changed but remember that the accompaniment plays on channel 9 thru 16.