How to use switches in examdesign package

I am reading the examdesign class documentation. On page 2, it mentions switches. I am trying to use the \BoldfaceCorrectMultipleChoiceAnswer switch. However, I don't know how to use it. The documentation says:

Switches should be included in the preamble because doing so will guarantee that they will apply to the entire exam.

So where should I put the \BoldfaceCorrectMultipleChoiceAnswer switch?

• preamble means between \documentclass and \begin{document} – David Carlisle Mar 4 '15 at 17:56

\documentclass{examdesign}