Not much of a user of the forum, though a very intensive user of PTE nowadays, I hope I'm in the right area!
I find the facility which links a sound file to a slide very helpful when things get complex, as they are doing with me now. Without it things would soon go hopelessly out of synch!
I'd like to suggest (I think I've mentioned it before) a simple change to the number (light blue on a white square) which appears on the sound file when it's linked to a slide. Could it please be in a more conspicuous colour (I would suggest white out of red as a good visible combination.)
In parallel with this, could I suggest a warning message when you remove a slide from the timeline, to flag up that there's one or more sound files linked to it. I have often lost bits of my soundtracks because I failed to notice that the sound had disappeared along with the picture!