If you experience that the audio and video are out of sync;
Verify if the Audio out delay feature in the [Setup] > [TV settings] > [Sound] > [Audio out delay] is set to [On] mode. This feature delays the digital audio out from the 'DIGITAL AUDIO OUT' and 'HDMI1 ARC' connection of the TV to the HTS.
If the delay is not optimized, you may change the setting of audio output delay in the [Setup] > [TV settings] > [Sound] > [Audio out offset]. You cannot select this setting if [Audio out delay] is not switched on.
Since a video signal is more complex than an audio signal, the TV will take longer to process. Due to this difference in processing time, your HTS may reproduce the sound before the picture appears on your TV.
Some Home Theatre Systems are equipped with a feature named 'audio delay' (or 'Lipsync' or 'audio sync') that will delay the audio signal in order to compensate for this difference in processing time.