: Keep the port on Auto Selection or manually choose the USB port labeled with your printer.

: Restores the internal counter to 0% so the printer can function again.

However, treat the adjustment program as a . The real solution is physical: install an external waste ink bottle. Once you have done that, you can run the adjustment program once a year for five years, and your Epson L121 will print tens of thousands of pages without ever bugging you again.