We need to restrict access to our odoo ecommerce site so that it can only be accessed by portal users and not the public.

I have been told we need to edit the web controller routing and set the value to auth="user" instead of public but have very limited coding knowledge, if anyone can advise how to access the correct area to make this change it would be greatly appreciated.

We are using odoo v12 hosted on odoo.sh and have odoo studio