You can
change the default paper size and paper type using the control
panel on the product.
Press the home button, if
necessary.
Press the arrow buttons to select Setup and press the OK button. You
see a screen like this:
Select Printer Setup and
press the OK button.
Select Paper Source
Setting and press the OK button.
Note:To prevent the paper setup screen from appearing
automatically when you load paper, select the Setup > Printer
Setup > Paper Source
Settings > Paper
Configuration setting and set it to Off. (This will also disable
AirPrint.)