Any slide can start playing different audio than the one set in Audio track. To do this, drag and drop an audio file from assets onto the particular slide in the row of slides at the top.
Such slide will be then marked with Audio sign and from that time new audio will play.
When you select that slide or any slide after it the new audio will appear in the Audio bar.
To delete the Audio Cut, select the slide with the audio change and click the x button on the Audio track.
To better see the different Audio changes in relation to the slides, switch to the Fine Adjust tab
When you re-arrange slides, the audio cut will be kept with the particular slide.