Audio out of sync after saving

[Tdr]

I've edited one of my video (via Avidemux 2.8.1) and saved it.
I use VLC media player to watch/playback my videos, but this one video, the audio is out of sync when I play it via VLC,
but when I play it with Avidemux the audio is in sync. so I can't use the Shift function, to try to match the video and audio seeing that they are in sync.   

this happened once before and I think I saved the video when I got the "The beginning frame is not a key frame".
  I think this video also had the error but I'm not sure.
 
any Idea how or why this happened? (note: I still have the unedited version can try editing it with any suggestion I get)

Thanks