Blender audio-visual don't sync PROXY

Hi , i´m having a big problem using blender as Video Editor, normally when i export my video, the video don´t sync the 50% proxy to full render, are in the diferents parts of the footage, and when i try to export, the video is different, I tried everything and i dont know how to solve this problem… I would love continue using blender as video editor, but if i cant solve this problem i will need to change for other video editor…