The icons represent the default player you have set for that type of file. My audio files have a blue winamp icon by them, my videos have a WMP icon, pics have a infranview icon, ect.

It goes by the file types e.g. mp3, m4a, wma, mpg, avi, ect. And the media players you have associated with them.

To my knowledge there isn't an option to allow itunes. Try putting the file extension at the end of the file your searching for: "Mary Had A Little Lamb.mp3"
for example.

Tips on searching here: How to find music

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