Unfortunately, none of the solutions above worked for me and I didn't really want to edit each video to synchronize the sound track. So, after a lot of trial and error, here is the solution I came up with.

After selecting "Save As" > "Save As Video", I changed the default 10 frames per second to 30 and rendered the video. When I opened it in VLC, the audio was still lagging far behind the video.

Next, I used "Handbrake" (free) to convert the .avi file to mp4. Handbrake miraculously corrected the out-of-sync problem without me having to tinker with any special settings!!! Hope this helps someone else...