(a) View a YouTube video explaining the device firmware. This will also show you how to check which firmware revisions are currently in your device. The latest available firmware versions are 1: Remote Radio (0x100); 2: Dongle Radio (0x100); 3: Remote Sensor (0x110).
(b) If you still want to proceed, view a YouTube video showing how to upgrade the device firmware.
(c) If you still want to proceed, get the latest firmware and a beta release of the (Windows only) OTA firmware upgrade utility here.
NOTE: As you saw in step (b), there are several steps involved in this process. Recall that order matters if you are updating the micro-controllers in charge of the RF communication: the Remote Radio firmware needs to be updated first, and the Dongle Radio firmware needs to be updated second. If you are updating only the Remote Sensor firmware you don't need to worry about order and can skip to the very last step shown in the video.