Repeatedly being asked to sign in to Apple Music

Having subscribed to Apple Music, it feels like every time I open my laptop to play a song, it tells me i need to sign in to Apple Music to play songs from it. I sign out of iTunes, sign back in again, and all is ok. Then the next time i pick my laptop up, the same again. It just doesn't seem to stop logged in. iPad and iPhone are fine, it just seems to be my laptop. I'm on El Capitan 10.11.1 It sounds trivial, but its really annoying having to enter your tines I.D. every time, and then i have to go to preferences to get my iCloud music to show as well, a royal pain in the a** !