Add Filter to Help Desk Web Page

Hello,

My organization is using the help desk on the customer service portal.

The "Cases Web View" determines what fields portal users see on the help desk web page. Out of the box, the help desk web page has two filters: 1) for created by (i.e. by current user or by user's organization), and 2) for status.

The ask is: how canI modify this web page, or the view to add a third filter?

Thank you in advance for your help!