Apple Soundtrack Pro 2 - Manual (Page 190)

190 Chapter 5 Working in the Timeline
To replace the source audio file in all clips using the same source file:
1 Select all occurrences of the clip for which you want to replace the source audio file,
following the steps described in “
Selecting Audio Clips in the Timeline ” on page 147.
Every clip using the same source audio file is selected.
2 In the Timeline, select the clip for which you want to replace the source audio.
3 In any media tab, Control-click the audio file that will replace the selected clip’s audio,
then choose Replace Selected Clips With [filename] from the shortcut menu.