Audacity is an audio recording and editing application. Audacity does not edit video, although Audacity may be able to import the audio data from video files if you have the necessary codecs installed (usually required FFmpeg).
I just opened the QuickTime video that I wanted to add the the audacity audio to and dragged and dropped onto the opened video and QuickTime did the rest super easy (I don’t know all of the audio sources it accepts but Wav works).
others: If you don’t know the answer then don’t answer, QuickTime may not be your product but audacity is and QuickTime users may be using it. I for one did a google search to find the answer which directed me to this thread. After seeing the unhelpful replies (which is shocking), I was determined to figured it out. I’m happy to help other members whether its an audacity product or not THE AUDACITY OF YOU.
Although Trebor does not use a Mac himself, the first link that he posted (a little over an hour after the original post) appear to provide sufficient information to get the job done with “Avidimux”. His second link is a bit lacking in detail, but the official QuickTime documentation should fill in the blanks.
This forum sometimes becomes very busy, so we don’t always have time to research detailed answers about using third party software, but where possible we make every effort to at least point users towards where they may find answers - for third party software, that is usually the official support channel for that software.