This EE video Micro Tutorial shows a great feature in the free version of Tracker Software's PDF-XChange Editor
. The feature is the ability to customize the highlighter tool in two ways. First, configure additional, custom colors. The initial installation sets up only seven different color highlighters: Blue, Gray, Green, Indigo, Purple, Red, and Yellow. Second, customize the subject given to each color highlighter. This can be done to the initial seven ones, as well as the custom colors that you add.
If this feature piques your interest in PDF-XChange Editor, here are three more five-minute EE video Micro Tutorials that show additional excellent features of the free version
of PDF-XChange Editor:
How to rotate pages in a PDF with free software - PDF-XChange Editor
How to OCR pages in a PDF with free software - PDF-XChange Editor
How to password-protect a PDF with free software - PDF-XChange Editor
As a disclaimer, I want to emphasize that I have no affiliation with this company and no financial interest in it whatsoever. I am simply a happy user/customer.