Stumped with default form setting - is this a rookie mistake?

Hello community,

I am experiencing a frustrating problem which is likely due to a rookie mistake. When submitting a request in our Workfront instance, the first question is "Select a request type". As soon as any value is selected, a second field then appears which is called "Marketing Support Request". This second field is a dropdown that contains two values (think of it as a request category).

I have a screenshot to better explain this. I can't for the life of me figure out how to change / update the values of that second field inside the red box. It's one of the first things we setup when launching our Workfront instance. I've even gone through all of our custom forms to see if it appears somewhere, but it's as if the field doesn't exist anywhere in our system.

Is this experience common and if so, does anyone know how I can update this default setting?

Thank you in advance.