This will depends on ARRIS device you have and also if you are using the app to manage your network. If you reply to me with the model number of the ARRIS unit I can show how to configure it or you can type the model of the unit next to words parental control on Google and you will get the instructions.

Using SBC app (Please refer to the below link)

Step 1: Select “parental control “

Step 2 :Create profile 

step 3 :Add device 

https://arris.secure.force.com/consumers/articles/General_FAQs/mAX-Routers-Parental-Control-Setup#User