The volume of the Sound Bar changes unexpectedly while watching content from YouTube or a set-top box.

This issue can be resolved by turning the A.VOL (Auto volume) setting On. Follow these steps to turn on the setting:
Note: When the A.VOL (Auto volume) setting is On, the volume adjusts automatically depending on the input signal or content from a connected device.

For HT-S20R/HT-S40R

1. On the remote control, press the MENU button.
2. Select AUDIO → A.VOL → ON.
   Note:  To select the item you want, press the ↑ (upper), ↓ ( lower), or ENTER button repeatedly. You can return to the previous layer by pressing the BACK button.
3. Press the MENU button to turn off the menu.