Lexus 2014 LX570 Owner's Manual page 578

3-4. Using the rear seat entertainment system
Changing the speaker output
Operation from the front seats
The rear seat display can be operated from the front seats.
STEP 1
578
LX570_OM_OM60L21U_(U)
To play the rear audio over the
speakers in the vehicle, turn
"Speaker Output" on.
Press the "AUDIO" button.