Canon PIXMA MG5550 - Manual (Page 12)

Character Entry
You can enter the characters when the keyboard is displayed on the printer. Follow the procedure below.
1. You can enter the characters when the keyboard is displayed on the printer's LCD.
Password entry is case sensitive so press the center Function button (A) accordingly to switch between lower case,
upper case and numeric characters.
2. Use the buttons (B) to select a character from the keyboard, then press the OK button to
select and move to the next character.
3. Repeat 1 and 2 to enter the remaining characters.