I thank you for your time and expertise in helping with my computer/printer problem. Before I had the chance to try your solution, my son came over and switched my printer from "landscape" mode to "portrait" mode. Somehow that corrected the sideways print, and it's now printing single pages, as it should. I don't know what else he did.
Like I said, I appreciate your efforts, and will click "accept". It's good to know there's someone out there to go to with computer problems.