Printout lines hard to see
Printers with a very high resolution, may draw very thin lines. This is because that by default, each line is one pixel wide. If you want to print at much over 300 DPI, you should adjust the Print Line Boldness.
Fix:
Go to the Printing tab on the Preferences form and select a degree of Print Line Boldness.
It's best to select an odd number, so the line will be centered. i.e.. 3x or 5x will draw lines three or five pixels in width.