Once you've added a sound to your content, you have a few simple sound editing options at your disposal:
Shift your sound in time: music, voice or sounds usually need to be synchronized with your visual content, so you will have to shift these objects in time to accomplish that. You can either shift the sound object within the Clip or move the Clip as a whole. Some users also put all audio objects in one single audio clip that spans the whole length of the video.
Modify the volume level of your sound: To do that, first select the sound in the Timeline (its background turns blue when selected). You will then see a Volume slider under Object Properties on the right side of the editor. Use this slider to select the volume level you want:
Split or crop your sound: First position the Playhead (the vertical red line) where you want to split the sound. Next, right-click the sound layer in the Timeline. Select “Split layer” in the right-click menu and your sound will be split over two layers:
After splitting your sound, you can either delete a part or move it in time. You can also change the length of the parts: just drag their edges left or right to hear more or less of the audio:
Add a Fade In or Fade Out effect to your sound: To do that, first select your sound and click the "Add Effect" button at the bottom of the Timeline:
You can adjust the length of the Fade effect by dragging the small border bullets to the left or the right:
Finally, you can also loop your sounds: when you drag the right edge of a sound to the right, beyond the length of the available audio, it will repeat the sound from the beginning. Fine vertical lines in the sound bar show where the loop repeats: