So usually the bottom of an app has the source information listed e.g. ESRI,NOAA,USGS etc. Is there a way to add more information to this? I have a client that wants to add the current username and maybe some copyright information. Is this possible to do?
Matt,
that information is pulled from the map services used in the map and their copyright information. So no unless you have access to change the copyright info for the services you are using.
There are two ways to edit this, you can do it in desktop before you publish or by updating the definition of an existing service:
How To: Modify the copyright text of a hosted feature service in ArcGIS Online