Epson printing from wrong cassette

I have a fairly nice Epson printer that is only a few months old. When I'm using my iPhone & iPad to print documents it's pulling from Cassette 1, where the 4x6 picture paper is. It should be pulling from Cassette 2, where the regular 8 1/2x11 paper is. Any suggestions on how to change it?

I did read an old Forum answer from 2012 that told how to change it from a Mac but when I typed in the link it didn't work. This is super frustrating! 🙂 Thanks in advance!