My Iphone 4-s music won't save on Itunes?

Anytime I create a playlist or change music on my phone, Itunes seems to keep changing it. I removed several songs from my phone for space, yet when I plug my phone into Itunes, the erased song re-appear and the playlists I created aren't there anymore after I disconnect the phone. This would not happen before because when I plugged the phone in, Itunes would update anything on the phone, instead it's the other way around now and anything on Itunes will remain on Phone is there anyway to prevent this from happening and get my phone back to normal?

Itunes always sync your phone when connected to pc/mac.while syncing it backs up your data lik… Sms.app data.contacts.settings… N copies any new apps tht u hv downloaded…
bt it dnt copy music or pictures from your phone directly… While syncing it copies music in its own playlist to your phone… So if you want 2 delete any music delete it from your itunes playlist n thn sync your phone with itunes…