audio copyrights?

[Pistol]

I created a video using standard Windows 10 Video Editor. It allowed me to choose an audio file in part of the program. When I put the video on You Tube, almost instantly, someone filed a dispute, claiming copyright infringement on the audio.

Can some one please explain this to me and what should I do?
Should I make the video Public Domain? Should I make it private?
Should I remove the audio (if so, there's no point in the video).

I thought choosing one of the audio files in Editor offered was like choosing a font in Word - it's public domain and available for everyone to use.

[coachwhip]

Not always true, I have experienced the same even after purchasing royalty free music from iTunes but oddly enough iMovie audio tracts have never been flagged but is limited. If you go your YouTube Creator panel and look up audio library you can find 1000s of free music files available to use on your videos, this is your best option for free.