New Macbook Air not updating

I've had this MacBook Air for a month now, brand-new. A new update came out a few weeks ago. Every time I try to update it, it wants to restart but does not, instead once the countdown to restart ends it tells me "Available updates have changed. Click "show details" to see the available updates." I click on that and the countdown starts again. It just repeats itself. I restarted it on my own a few times but it still says there is an update.