In the view 'Global credentials' (http://localhost:8080/credential-store/domain/_/) the available credentials are listed. After selecting one, a new empty screen opens that shows only the user ID of the credential. In order to edit the properties, you need an additional link in the side panel to open the next screen (btw: the link should be called edit rather than update).
It would improve the usability if the editable properties would already be shown in the first screen. A second screen is not necessary.