Changing printer paper size on iPad
If you always get a paper size of 6x4 photo paper size from your iPad when printing. On a canon printer check your printer and change you rear paper tray to A4 paper and then the ipad will print at A4 from then on. It’s something with the Canon printer not communicating with the iPad. I had this problem with my iPad, until I changed my rear tray to A4. The problem went away. Hope that helps.
iPad mini, iOS 9