When printing from your wireless devices via Apple AirPrint, the paper size and tray that will be printed from is selected automatically according to the application software being used on the device, and the region in which AirPrint is used. When Apple's photo application software is used, the default paper size is 4x6, so the printer will feed from the upper cassette tray. If you want to print in another paper size such as 8x10 or from the lower cassette, you will need to use a program that has that paper size as a selectable option and print from that program to the printer.
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