Airpods connected but play sound out of phone

when I connect my airpods, the headphones icon appears at the top of the screen but the sound still plays out of my phone. I’ve tried resetting my airpods, my software is up to date (it’s happened before and this is us usually the problem) and when i go to airplay in control center it shows it’s playing through ‘iphone’ and won’t let me click the ‘airpods’ at all!