Latency on your recording device is usually the issue. Some devices are notorious for this. If you research this the device sometimes has a buffer setting that will compensate. How much is it off?
Adrian_Hunter maybe I misunderstood. If you have a negative number for your sync value the video to audio sync may be off. To correct this you can edit the track and shave off the time differential to zero and that would correct that. The other issue is if your cam is buffering. For instance I use a background changer to hide my background. This sometimes causes that issue as the image or video running in the background needs to buffer. The more complex the images the more chance of video to audio sync difference.
I tried shaving of some from the start of my video and uploaded it again, but then I got trouble in the DAW when correcting the sync a little, it did not save the adjustments in the main studio.
I find the sync between sound and video is off when I upload a file, how is that possible ?