When the designer saves a report, it needs access to table information from the NAV database where the report object is stored. It will use either the OData web service or a text file containing all the exported tables from NAV.
The designer can read information about where to get this information in two different locations. First it will look at the report properties in the designer. One of the properties can hold the OData URL or the file name. If this property is not empty, it will be used. In case it is empty, the designer will try to use the global settings for the designer. The global settings are set in a configuration dialog in the designer.
Information about the OData web service is transferred from NAV to the designer when you open the designer from the request page of the report. It will check the NAV installation that launches the designer and see if the OData service is configured. If the web service is there it will pass the URL of the service to the designer and set the report property to that value. Therefore, the designer will not use the global designer setting for table definitions.
Please note that if your web service for some reason does not work then you must remove it from your NAV list of web services. Otherwise, it will be passed to the designer each time the designer is launched from the report request page.