You can pair the Happy Plugs Play products with multiple Bluetooth devices. The headphones stores and remembers these pairings. However, you can only be connected to one device at a time, e.g. play music from one Bluetooth device.
To change from one Bluetooth device to another, disconnect the current Bluetooth connection by switching off Bluetooth at the current device and connect to your second Bluetooth device by selecting the Happy Plugs Play product entry in the Bluetooth menu.
When you turn your Happy Plugs Play product ON it will automatically connect to the last device you were connected to.