sync issues with iTunes

I have a iMac, an iPhone and a MacBook pro... I mostly use the notebook+iphone... I buy most of my itens using the notebook... today I decide to sync my iPhone to the mac... what I noticed is that a lot of songs that ARE on the phone did not get transferred to the mac... but some did...

why? how can I make all the songs in the phone "go" to the mac without re-download? (its about 3gb of videos-musics...)

PS: "sync all lib + videos and notes" is on