Do not follow the instructions of Biggles - you need no backup, no SaveAllFile, no download of OS and no OS update.
Simply go to the Global > General Controls > Lock > Control page.
Select/deselect the desired lock "Lower".
When this lock is closed, the Lower Sound remains unchanged when a different Keyboard Set or Style is selected.
This is useful if, for example, you prefer to only play chords with the left hand, while leaving the Sound in mute.
Only if you want the same Lower settings to be used during all your shows, save your preferred Lower settings to the MY SETTING
Keyboard Set (automatically selected on startup), and close this lock.