Thank you for all of the prompt replies! I'll address each one.
Xerox: I tried putting the Smartsound track in the voiceover track (instead of the music track), and adjusting the volume still had no effect on what I was hearing.
Dave: It definitely seems like adjusting the volume should be straightforward.I definitely had no problems with it in PowerDirector 8.
Barry: like I mentioned, I also thought that I should be able to treat the Smartsound like any other music or audio file. That's what makes this so frustrating! I'm trying to use the Sly version of "It's Cool", but I have also tried this with other files that came with PowerDirector 9. I'm not able to adjust the volume of any of the Smartsound options. I am indeed using Quicktracks version 5.8.1.0.
Tony: This was exactly the method I was trying to use. My preferred method was adjusting the levels in the audio room, but I also attempted adjusting the levels directly in the timeline.
Carl: I like your creative work around to be able to adjust the volume. It's definitely a few extra steps, but it sounds like it should work. A downside is certainly the fact that the length of the Smartsound track could no longer be adjusted once producing and reinserting into the timeline.
I would still like to hear if anyone else has any more ideas as to why adjusting the volume levels is not having an effect. Based on some of your input, it sounds like there could be a glitch in my copy. It sounds like other people are able to change the volume, but for some reason mine is not working.