Follow these steps to troubleshoot the audio video synchronization:

1. Check if the problem is seen with multiple sources of content (e.g. streaming video, DVD, local file, etc.)
2. Check the display settings of your TV for audio and video settings and ensure they're properly calibrated
3. Check any additional audio output devices (i.e. sound bar, Home Theatre System, or other audio outputs) for proper connections and sound settings
4. Check the cable connections between devices (HDMI, optical) and make sure they are secure
5. Ensure there aren’t any loose wires or other sources of interference in the area