Excellent question. In your Jtest 9.5 Eclipse IDE, go to the Help menu and select Help Contents. In the documentation tree on the left, go to:
Parasoft Jtest User's Guide > Static Code Analysis > Modifying Rule Categories, IDs, Names, and Severity Levels.
Parasoft's documentation is comprehensive and easy to follow. Plus, it's very easy to search because it is built into Eclipse.
If you have any questions that are not clear from the documentation, or if you have ideas for new features, Parasoft's Support Team is very helpful and normally responds within a few minutes. You can contact them by going to www.parasoft.com and selecting the "Support" link at the top of the page.
Full disclosure: I am a Parasoft employee.