By default, chat widgets are displayed on a customer portal for a configured project or on an external web pages. However, if you have multiple service projects, it is possible to also show the chat widget on the main page of your customer portal (a.k.a. "Help Center"). To do this, you need to select which chat should be used, as the main page of the customer portal does not yet specify the project to be used.
To select a chat to be displayed on the main customer portal page, pick the default chat project from the dropdown, as shown below: