Hi Jim and welcome to the forum The answer to your question is very straightforward.
Assuming you have your sound set-up saved in a Panel Memory, Press Program Menus > Sound > Part Setting. Use the buttons at the top left to select the sound whose octave you wish to change (RT1, RT2 or Left) then use the Key Shift buttons to set the Key Shift to -12. Press and hold the SET button in the middle of Panel Memories and then press the Panel Memory in which you wish to save the new setup. This could be your original Sound Memory or any other Sound Memory. Press Program Menus to return to the Home Screen and then Save your new setup to SD card, as normal.
Another way of achieving an octave shift for RT1 and RT2 voices, is simply to press the Octave Shift key on the front panel. You can then save this setup in a Panel Memory.
Yet another method is to edit the existing Piano sound in the Sound Edit facility, reduce the pitch by 12 semitones and save this as a 'new' sound in Sound Memory. You can then call up this 'New' Piano sound for use, as required.


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Willum