Input Functions - Motorola MT100-5-SB20 User Manual

Press the power on/off button on the remote control or
Optical in: Connect a compatible device to the OPTICAL input on the
soundbar using a digital optical cable (not provided with the product).
Select OPT mode either by pressing the OPT button on your remote
control or repeatedly pressing the MODE button on the soundbar control
panel until OPT is displayed on the LED display. Ensure Optical SPDIF is
selected as the TV's audio output, then adjust the volume of the soundbar
using the Volume Up and Volume Down buttons on the remote control or
soundbar control panel.