The Transpose function makes it possible to shift the pitch of the YPP50 +\- 6 semitones.
1) Press and hold the [MIDI/TRANSPOSE] button.
2) Press the [TEMPO UP] or [TEMPO DOWN] button as many times as necessary to attain the desired transposition level amount.
NOTE: Each time the [TEMPO UP]] or [TEMPO DOWN] button is pressed, the pitch of the entire keyboard is transposed up or down 1 semitone.
3) Release the [MIDI/TRANSPOSE] button.
Reference: Owner's Manual, p.8
Do you need an additional help?