My 17″ Macbook Pro died last November. I have a new Macbook running 10.9.3 but my iPhone 4 won't sync wirelessly because it's still looking for the old Mac. I cant find a place to make it forget the old one and sync via wifi with my new one?
You need to sync your iPhone with your new Mac using USB. After you've done so, there is a check box to sync using WiFi in the iPhone's tab in iTunes.
Be careful though, if you sync with your new Mac, and you haven't transferred your media to your new Mac from your old Mac, you will lose the media on your iPhone.