I am having the same problem today. The settings under Edit/Preferences/Editing appear to control the Editing area of the software.
This thread appears to identify a problem in the Create Disc area. In the Author screen, there is a field titled "Background Music". There are four icons following. If you hit the {MusicalNote}+ icon, there is a field called "Duration".
Duration appears to be able to be increased by dragging the right slider bar in the box above.
Moving the slider bar, you can watch the Duration field increase. But when you hit the checkmark to save, and then come back in, the Duration field is set back to 4 seconds.
Your assistance would be greatly appreciated.
Brady