Printing from my ipad and iPhone go to the rear tray on a cannon 6020 and I can not change it to the main tray
How do I get a cannon g6020 to select the main tray when printing from an iPad or iPhone
iPad 2, iOS 9
Assuming that you are using native AirPrint, any available printing options will be visible from the print dialogue.
By example (your printer will likely differ):
If you are instead using a companion print App intended for your Cannon Printer, you might instead find printing options within the App itself.