It depends on the project settings you selected when you started your Premiere Elements project -- and, of course, which version of the software you're using and what model of camcorder your video is coming from.
For just the Program Monitor, setting that to Fit, will be correct - however, your Project Preset MUST match you Source Footage. Are you mixing Source Footage, or mis-matching the Project's Settings to your Source Footage?
Thanks. I forgot that you have to make that setting before you create the project. What was frustrating me is that after I erroneously created the project, “Fit” only zooms the image, but maintains the same aspect ratio.