No drop down menu below iPhone in iTunes

Hello,

When I plug my phone into my new computer, there is no arrow next to the phone to click on to access the drop down menu (which shows playlists, movies, books, etc on the iPhone). When I plug it into my old macbook pro, this arrow is present. I would rather my new macbook be the primary computer for updating, so switching this would be fine. But if somehow both computers could access the media that would be great. Any help would be appreciated.

Jeremy