Hi
If everything IS working as it should, you can left click the soundtrack for the clip in question to select it and it will appear in the left hand preview pane.
Across the centre you should see a blue line. This line can be grabbed with the cursor and pulled down or lifted to different heights at any point along its length and when released will leave a small square marker. You can do this at multiple ponts along the length of the clip creating fade ins and outs.
If you start by grabbing the left hand end of the line and pulling it down to the very bottom of the preview window, the volume of the clip will be reduced to virtually nothing although you will be able to hear it faintly.
To mute the clip entirely, select it and then click the small loudspeaker button situated on the far left of the audio track in question.
Right clicking the track gives a menu with further options.
These controls should be sufficient for most commonly used tasks in editing.
VP provided several sound effects that can be applied to the audio track of a clip and these are selected by either clicking the "Effects" button on the toolbar which will open the Audio Effects window directly and from which you have to click the Add Effect button,
or you can also click the small arrow to the right of the toolbar button and selection "Audio Effects" from the bottom of the list that appears followed by the effect that you require.
This opens an effects window containing controls for the effect and a preview of the soundtrack similar to the main one described above.
If none of this happens then obviously there is a fault with the version you have.
If you want to go back to an earlier version of VP then at least Save your project before you do so. Not sure now if 2.41 is available from the usual download sites as NCH update these with the later versions as they come on stream (although they don't change the images associated with these 
)
Provided you save the .exe (vpsetup.exe) file for any downloads you do then you can easily switch back to your original version if things don't work out. However...an earlier version of VP like 2.41 will not load your project from version 3.xxx as the files are saved in a different
form.
Nat