Modifying individual key volume

[Pianosaurs]

I looked all over the place but could not find out where this feature is located.

On the RD-700, how do I change the sensitivity/volume for each individual key when it is pressed??

I remember doing it a long time ago and there was this chart on the keyboard display.
I looked on this forum and google and the rd-700 manual but could not for the life of me locate that function...