I can share some information about turning off double-sided check printing in QuickBooks so you can successfully print them, ralred.
QuickBooks Online doesn't keep Printer Settings. In your Windows Printer settings, you have the option to select either one-sided or two-sided print, as well as paper feed preferences.
If your printer preferences are not being saved, I suggest contacting your printer's manufacturer or your IT professional. This issue appears to be related to either a Windows or driver problem.
Keep your posts coming if you need further assistance in printing checks. I'm always here to help. Have a great day!