Every time I upgrade the iTunes software it loses my music, ratings and playlists. Any way to stop that?

The lady 5 times I have upgraded iTunes it loses playlists, ratings and I have to scan for music

again. I stopped upgrading but my son was using the puter and clicked the dreaded upgrade button. Lost it all again. Once I deleted all the iTunes stuff on the outer and reloaded. Still lost when upgrading. Is there a way to stop this from happening?