Why my labels are not sharp / dark？

A:
Try to choose PDF file format for printing instead of PNG, PIG and other image formats

For Windows:

You can do this by entering:
Settings -> Devices -> Printers and Scanners -> Right-click on 'Munbyn ITPP941' -> Manager -> Printing Preferences -> Page Setup -> Density/Speed.

For Mac:

1).Choose printer features

2).Adjust the density, Try to choose low speed while high density