There is a problem in the Quartus® II software when the Bus Display Format in the SignalTap II waveform file is set to Signed Line Chart. When Signed Line Chart is set as the Bus Display Format, the results instead print out in the Unsigned Decimal format.
This issue may be addressed in a future version of the Quartus II software.
As a workaround, export the waveform into a graphical file format (such as .jpg or .bmp) before printing. On the Quartus II File menu, click Export, and then choose either JPEG (.jpg) or Bitmap (.bmp) file format.