These tips did the trick, at least initially! And now I must be doing something wrong again - I have more images and a couple more video files that I need to add to the sequence, but whenever I make any changes I lose sound. Sound comes back when I undo changes until just before the point I add pictures to the images folder (Note: I can add images to the staging area, and the sound still works. It isn't until I try to add an image to the sequence that I lose sound. I have to back out to the point before I added pictures for the sound to come back).
Steps to add: Drag picture and snap to line in between video and other image = lose sound. Add picture to the end of the sequence = lose sound. Add picture to the very beginning of sequence = lose sound. In every step, I am dragging and snapping the image to the sequence.
Than you so much for your help, I'm not sure what I'm doing!