Click the Edit icon to display the Edit Server dialog:Modify the backend server details. These options are the same as those you configure when you define a backend. Depending on whether it's a local or in-source server, you'll see slightly different fields:
In Server Identification, under Instance URL, change the modifiable portion (the part that isn't grayed out) of the instance URL or the description. If this is an in-source server, you can also change the server variables (described in Add Server Variables for Backends).
In Headers, under Custom Headers, use + Add Header to add static headers that are passed from the browser to the service (although it's preferable to use the backend's headers rather than those on this tab—see step 4 in this procedure).