Datasource cannot be changed using graphical editors.
Currently it is not possible to reconfigure the location attribute of the ToolAdapter model instances without directly opening up the xmi model via the plugin's pathmap.
Won't fix that in the current editors; the current UI support is for developers only and in incubation state. Real graphical editors with full specification support exist in the CloudScale IDE. After the project is over, we will plan an integration to Palladio of such editors. Accordingly, this issue is a new feature request to be coped with in the future.