Hi, I avoid this with my videos simply because the answer is either you can't, you have to argue it with YT/Magix or use one of YT's royalty free sound tracks, you don't have permission to use the sound tracks within Magix, even if you buy that track from the Magix store it's not yours to use on a monetised vid in YT.
I'm sure someone will clarify tis for you but like i say i avoid it, YT has some policies on using other's music but you'd be better searching YT for that answer.
If I'm wrong it'd be good to hear because i tried many yrs ago n got told off / flagged by YT. so haven't tried since.
PS. it's a bit like if you buy a cd, download a track etc.. you can't then play that track at a public event where you financially benefit from it.
Here is the latest time recently when Facebook is informing me I am doing some sort of copyright infringement by using this soundtrack with the video generated by this software I bought. If Sony (SME) has the copyright to the music, what are the odds something similar enough got randomly generated by MusicMaker?