Why can't I move my songs in my iPhone?

I bought a MacBook Pro a few days ago and before I had an iMac. I always added and edited songs on my iPhone on my iMac, but now, I can’t do any of that anymore because this is what my iTunes looks like when I select my iPhone on my MacBook. I can’t play the music nor drag them to playlists, but all those songs were added from my MacBook.

What’s wrong and how can I get it back to the way it was on my iMac?

(btw, I already restored its original settings)