If your TV's audio and video do not match in the way they are supposed to the picture and sound are said to be "out of sync." There are a number of reasons this could happen. Sometimes a signal being broadcast by a TV station will come with out-of-sync audio and video. Though it is rare, in the event that this happens there is nothing you can do because the problem is not in your TV. There are, however, a few things you can do to correct out-of-sync audio and video in other circumstances.
Make sure the coaxial cable that is connected to the back of your television is screwed in tightly and securely. Whether you're using a cable box or an antenna to receive television signals, if the coaxial cable that runs from either of those two devices to your TV is not screwed into your television properly it could cause the audio and video to go out of sync.
Flip through the channels to see if the problem is happening on all channels or just one. If the audio and video is out of sync on one specific channel, the problem lies with your cable service provider and not with your set-up.
Make sure any external devices you are trying to use are plugged in properly. If the audio and video are out of sync on a DVD player, Blu-Ray player or video game console make sure the audio and video cables that run from the device to your television are plugged in properly. If they are not, this could lead to out-of-sync audio and video.
Turn off "Game" mode. Newer LCD and plasma television sets come with an option called "Game" mode that adjusts the audio and video to remove any delay that may be present when playing video games. If left on while watching TV, this could cause the audio and video to be slightly out of sync. Use your television's remote control to enter the device's main menu and turn off "Game" mode.