Hi chs117,
Your sound should auto-sync when both devices are turned on.
But if not, you should have something similar to 'AV Sync' on the soundbar remote. You'll be able to make slight changes using that.
You should check that you are using a suitable HDMI cable too, as some can't handle the sound precisely.
Is there an issue using the optical option, I have mine set to Bluetooth as there never seems to be any sync issues.
Steve
Utrinque Paratus