You can change the value of the metadata items in the Value field. 
            When you edit the value of a metadata item, a small red triangle appears
                        at the top left hand corner of the Value
                        field to indicate that the field has been modified but not saved. Click the
                            Save button if you want to apply your
                        changes.
            Example
            Alternatively you can select the Advanced
                            Edit check box in the Metadata tab to edit the service metadata in text mode, for
                        example, to add or delete a metadata item, which can not be done in grid
                        mode. Validation errors are highlighted automatically when you edit. An
                        exception will be reported when you save the service metadata with
                        validation errors.
            Example
            The service metadata can be removed by clicking the Remove button.
            For services that does not have metadata, the Create button is enabled. A sample metadata is provided when
                        you click the Create button. You can change
                        it as needed.