The smart-mirror is configured using the Remote Configuration Tool. This requires you starting the mirror.
Open the terminal and type:
If you're running the mirror for the first time (or for the first time since running upgrading to this version of the mirror) you'll see a QR Code with a URL under it. From a phone or another computer (on the same network as your Smart-Mirror) you can open a browser and manually enter the URL.
If you're not running the mirror for the first time and you've properly configured the Sound and Voice, say the keyword/hotword and then "Show Remote Link" to display the URL to reach the Remote Configuration Tool.
After going to the Home page click on Settings > Configure the Mirror.
Next Step: Configure the smart-mirror