To reset the 20 digit WiFi Password to a more useable 8 digits, go to a web browser and type livebox into the address bar. If that doesn’t work type 192.168.1.1
It will then ask for the password, it is usually the first 8 digits of the WiFi password, if not that click on first time use below and follow the instructions.
Once logged into the Livebox you can change the language to English on the link at the top. Then click on the WiFi tab along the top.
Click on advanced WiFi on the left hand menu. Scroll down to Security Key and click on Modify and then enter your new password and click on Save. Go to the bottom of the page and click Save.
Remember if your device is connected by WiFi then you will be logged off, you need to go into your device and forget the old network and reconnect.