You can use the Kidde app to update the software. There will be an option to update on the Kidde app dashboard when there is a software update available.

Click on the alarm you would like to update. Show Settings -> Update Firmware. This will be enabled only when there is an update available. Repeat these steps if there are multiple smart alarms in your network. Your mobile phone must be connected to the same Wi-Fi network as the alarms you would like to update.