This helped, but with modification that others might want to know about. I do not have a "Show Details" button. But this is what I did:
1. Open a document you want to print.
2. Go to "File > Print" or "Command-P." A Print window opens.
3. Click on "Copies and Pages." Options open.
4. Click on "Layout." Near the bottom, notice "Two-Sided."
5. Click on the arrows for "Two-Sided."
6. Click "Off."
7. Click "Print." Problem solved!