Multi-Timbral Setup

1. Select MIDI Mode 'Multi' in Master Menu.
2. Go to Midimap Menu > MIDI Enables.
3. Turn 'All Messages' Off for channels not used.
4. Assign Presets/Hyperpresets to desired MIDI channels in Midimap Menu.
5. Save the Midimap.

Source: Ultra Proteus — ultraproteusownersmanual (manual)