Hello experts,
Unfortunately I have a problem with the adaptation of the form for resolving a case.
I would like to add another field to this form:

The problem is that no matter which form I change, nothing happens with this one. What type is this form actually?
If I have understood correctly, the adjustment happens in the entity 'Case Resolution'. Here I have the following forms available:

During my research I came across the following page:
https://docs.microsoft.com/en-us/dynamics365/customer-service/modify-case-resolution-dialog
It describes the following approach:

Unfortunately, this option is also not apparent to me:

I hope that someone can help me in this regard and thank you in advance.
Kind regards,
Daniel