music not transferring from pc to nexus 7

hi hoping someone can help!I got my nexus 7 for Christmas then had to return it to Dixon's as there was a problem with the screen aside from that it was working fine and had transferred all my music from iTunes on my PC to the nexus and even when I put new music on my iTunes it was automatically going onto the nexus.I then got my new nexus and everything was fine everything was automatically on it all my music,books etc.But I have since downloaded new music to my iTunes which appears to be o my PC and on Google music manager but is not on the nexus.I am puzzled as to why its not automatically transferring please can someone help and explain simply as I'm new to android and nexus and clueless!

First off, I assume you are using Google's Play Music on the N7 and Google Music Manager on the PC.

Now, make sure you are logged into the same account on both devices. Running GPM on the N7 should give you access to all the tracks in your account (i.e. in the cloud). If you want any of them to be physically on the N7, you have to select "keep on device". Though, if you have selected "automatically cache" it will try to keep a lot of music on the N7 - it's not clear to me how the player decides what to cache, though..

To get the music manager to upload new tracks into the cloud, you need to have the root folder of your music listed in the box under the upload tab AND select "start automatically" under the advanced tab. Also, under the advanced tab you can see the account that you are logged into. Your N7 should also be logged into that account.