i have this screen. In the middle in the green field, the number that is there should be a customer number. Now I click on the button (sheet with the plus) to be able to create a new data record for this customer. This new data record should then appear in the yellow gallery after saving.

Now I have clicked the button and this screen appears.

Now I would like to achieve that the field "FZ_ID_KD" is displayed in the form with, but can no longer be edited, because that is the customer number from the moment and it should no longer be changed.
How do I manage to only display this individual field but not be able to edit it?
Best regards
RoScha