Your Essentials Wi-Fi Powerline's settings can be changed using your regular web browser and browsing to its IP address. The easiest way to do this if you don’t know the address of your Essentials Wi-Fi Powerline is to download and install the BT Device Configuration Tool.
Click here for full instructions.
Once you’ve logged into the settings interface, your wireless network name and key can be edited on the first screen that appears. Help is provided through the link on the right of the page.