Error with primary display property while creating new custom object with the API tool

[JBrillinger]

I'm using the Object Definition tab/tool in the developers.hubspot.com api docs.
I am using the create new schema section to create my code.
I've completed all sections and there is no section to enter the primary display property. Of course when I call, the error response is invalid primary display property.
I'm not able to edit it directly in the Request code window either. There I see it set as: "primaryDisplayProperty": "my_object_property",

Is something wrong with the Object Definition tool?
Or what do I need to do to get it to give me the option to edit the primary display property? 

[JBrillinger · Accepted solution]

I have just discovered the 'See all params' button. 
That did it!

Solved my own first issue 🙂