The Octave buttons on the front panel are offsets that are applied when you activate them. If you want to store a Part of your current Performance with a different octave tuning, you would need to edit the Performance Part. The parameter is called “Note Shift”
The Octave buttons effect the entire keyboard
The Note Shift parameter can be stored on a per Part basis.
Select “Play Mode”
Find the “Note Shift” parameter
-/+12 steps is an Octave
You can raise or lower the Part -/+24 or two octaves.
Make your setting, press [STORE]