its just the downloaded version.. if it was download by itunes then maybe the album or download was made like that. if not downloaded by itunes then maybe get a different version. to get the same song, but in a better version do this..
go here -> clipconverter.cc
open new tab
go to youtube
search your song name
click the song that is the best to your liking
copy the URL
paste the URL to clipconverter.cc
make sure it's under MP3
then press continue
a "start" button should appear at the bottom.
when the video is done you can download it and drag it to itunes
hope i helped!