if you're like me your movies that you play/stream from your phone to your smart tv are beginning to play up. The picture isn't matching the sound anymore and character's lips are out of sink with the movie making them unwatchable. No matter what you try you can't fix it. You've done everything, deleted and reloaded the apps associated with this function like google home app & have even gone to a popular phone cleaning app, to clear all of the unwanted snippets of information that is clogging up your phones operational efficiency called (cached files) or just the ' cache' if you've tried this last method then you're on the right track. However, these apps although they say they clean residual cache, quite often they don't do that at all. You were on the right track though. The best way to make your movies play smoothly and properly is exactly that "clear or clean the cache" but unfortunately the only true way to do it properly that I have found is to find the apps associated with what you are having problems with and clear the cache individually. For instance, for movies you'd have to go to the Settings/apps/"Google Home"/ storage/ clear cache, down at the bottom of the screen. /Back.
Then you would try some others associated with the playing of movies like, VLC or Popcorn time etc, or just any other app that you think could be associated with playing or sending a movie to your tv yes! Then do the same with your smart tv. Go into the settings find the apps find the Google Chromecast app/ or as I said any app that sounds like it has something to do with playing movies on your screen and clear the cache. Turn your phone & tv off and back on, reconnect to the phone and the net. Open your phones 'My files' folder select 'videos' to see all of the video files on your phone, select one you know works then select the player to use as usual, in my case VLC is my default player because it's sturdy and reliable. Play the movie. Check now for out of sync voices with the actors on the screen. It should be ok now. I have a cheaper model 4k smart tele( Kogan, although a great tele) & it's always had a little bit of skipping or looks like slow frame rate when something moves fast across the screen, but I imagine on a premium brand this will also disappear. I hardly notice this after a while on my Kogan anyway. But anyway the main bulk of your problem should be fixed. If it's still playing out of mesh with the sound, check that you've cleared all of the main apps cache and haven't missed any ok. You should now be able to download and play movies again from your phone, please comment if this has helped you. Thankyou
Thanks for sharing @Insanenitro