Thanks for your quick response.
Let me correct my previous statement. The printer grabs from tray 2 (8.5x14) by default when making photocopy. It grabs paper from tray 4 if manully select tray 4. If I don't select tray 4 before copying, it will grab paper from tray 2, which has 8.5x14.
Printing seems to be fine. It always default and gets paper from tray 4.
I see tray 4 settings for paper size is A4 (210 x 297 mm) and I cannot change it to Letter (8.5x11").