To upgrade you InvizBox Go to the latest available firmware, you need to login to the web interface by using http://inviz.box (or if you are connected to alternative networks, by using directly the device IP address http://10.153.146.1).
If a new firmware is available, there will by a pop-up window at the top of all pags which provides a link to install that new version. You just need to click it to perform an upgrade.
During the upgrade, the InvizboxGo will keep your settings (for example the VPN username/password, the admin interface password, your known Wi-Fi networks/paswords)
Your InvizBox Go is checking for the availability of a new firmware roughly every 30 minutes.
Your Invizbox Go needs to be successfully connected to the internet in order to check for firmware updates.
Note: If you know there is a new firmware available but your device is not showing the pop-up window, there are cases where a reboot is required (and wait about 30 minutes).