Here is how:
1. Printer should be turned on, but not printing
2. Hold down PAUSE button for 3 seconds. The pause light will flash and the 2 tear off (FONT) lights shows the current font selected
3. Press Tear off(FONT) button to cycle thru fonts till light indicate the font you want. When you select the font needed it stays in use as default till you change it.
Note: Some software can change the printer font selected.
If need more information about your printer
check the manual