Printer uses the wrong paper size or tray
If the printer asks for different paper or pulls from the wrong tray, the printer and computer may simply disagree about what paper is loaded.
1. Check the paper in the tray
Look at what is actually loaded. Letter and A4 are different sizes. If the printer has a screen, make sure the tray shows the same paper size and type.
2. Windows
Open the Print window and check Paper Size and Paper Source or Tray. Choose the size that is really loaded.
3. Mac
Choose File → Print and check Paper Size. If the printer has several trays, look for Feed From or a similar tray choice.
4. If the settings already match
Open and close the tray normally, make sure the paper guides fit the stack, and check the printer screen again. Some printers ask you to confirm the paper size when a tray is opened.
5. Try one page
Correct only the setting that was wrong, then print one page. If it works, stop there—there is no need to reset the printer.