KORG PA4X 76 - Manual (Page 164)

160| Customizing and editing the Sound sets
Choosing (and viewing) the FX group
In Style Play and Song Play mode, the FX group is fixed and cannot be
changed (you can only see it). In Sequencer mode you can freely choose it
for each Song track.
1 Go to the Mixer/Tuning > Insert FX or FX Send page.
FX group
FX group
2 See, or choose the FX group (this latter is only possible in Sequencer mode).