To enable multipoint, first enter pairing mode and connect to the first device. Once the first device is connected, enter pairing mode again - the first device will disconnect. Now connect to the second device and power OFF your headphones. Turn the headphones back ON and they will automatically connect to both the first and second devices simultaneously.
To switch between devices when connected with multipoint, simply pause playback on the first device and resume audio from the second - the headphones will swap to the device actively playing audio.
Over time, your headphones will accumulate a list of devices and may take longer to pair than anticipated. A factory reset can help speed up this process by forgetting the list of previously connected devices.