Video Editing Question. Audio out of sync. High speed

There is a website that I upload short / small video files to.
And very often on this site when I upload the small video
The audio is super fast. Like too fast. It's going much faster
Than its suppose to. So it sounds like the chipmunks and then
Very quickly it goes silent because the audio has run out. It's over.

Does anyone know why it's doing this and how ii can stop get from happening ?

The same Files when uploaded to Facebook and Tumblr are perfectly fine
It's only on that site that like every other upload goes all high speed chipmunk.

Video Editing Question. Audio out of sync. High speed