No sound in iMovie of video recording using the Screen Recorder
If your iMovie project appears to be missing audio tracks when you play, import, or export a project, try these steps first:


Make sure the audio track has not been muted in the timeline.
See if the volume in iMovie is set to its lowest, if this is the case, set the volume slider to maximum.
Make sure the computer's audio is not muted.
Quit and reopen iMovie, then check the clip to see if it now plays with audio.
Quit and reopen iMovie, then reimport the footage. Play the newly imported footage and see if you now have audio.
Check /Library/QuickTime/ and ~/Library/QuickTime/ for any third-party plugins. Remove them if present, log out, and log back in. Check to see if the issue persists. If not, check with the manufacturer of the disabled plugin to see if an update is available. Note: The tilde (~) represents your Home directory.
Check to see if any of the video clips you have imported are in the MPEG-1 format. MPEG-1 clips will lose audio when you export them as part of your iMovie project. 


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