Canon InkJet iX7000 printer kept printing from manual tray

User’s Canon InkJet iX7000 Printer kept printing from manual tray in Outlook even though:
a) Cassette has paper
b) In printer properties, Paper Source is Manual Tray as default even i changed it to Cassette
c) In Word, Paper Source can select to Cassette and print out from Cassette.

1) In Outlook, go to Paper Setup and changed to Cassette for Paper Source.
2) In Printer properties, Paper Source also “auto-changed” to Cassette
3) User able to print using paper from Printer’s Cassette.