Audio layer in video

Every video clip has an audio layer. You can change the overall volume of a video clip. To do more editing, you must extract the audio layer by clicking on the clip and selecting "Advanced" -> "Extract Audio". The extracted audio will appear in the Timeline viewer below the video clip in the 1st audio track.

The video clip will automatically mute, but it will still have the audio layer. If you unmute it after you split it, you may create audio problems.