Hello. I have a set of AirPods that are working well on my iPhone 6s and iPad mini 4. However, I can't get them to pair to my iMac and MacBook. They are all signed into the same iCloud account, Bluetooth is enabled on each device, and all are fully updated. Do I have to do something to get these to pair? The keynote made it look so easy, and it doesn't work. Any ideas? Thanks.