Canon BJ-20 User Manual page 60

4
Use a ballpoint pen (or similar object) to set the switches.
Caution
Changes should be done when the printer is turned off;
otherwise the changes will not be reflected in the current printing
session.
Choosing Between Print Quality and Speed
By default, the printer prints at high quality - 83 characters per second
(cps). For some work where speed is more important than print quality,