Hello Rose, yes this can be a bit of a training issue for clients. They see the 'open in excel' button and dutifully click on it. What happens then is like when you open an excel file from your desktop that has a data connection. At this point it is not
running under secure store but tries to connect to the database specified in the connection string using your logged in credentials.
Have them download a snapshot instead.
As stated you can set up people in the report authors AD group. This would give them data reader rights.
One warning from my experience however is that then this person can now write and execute queries against your reporting database. If the queries are malformed they can bring the database server down to its knees. If the reporting server is the
same server as where the other project server databases are then the person running queries can affect the performance and experience of ALL other users on the server. Not good.
good luck!
Ray Letts Arbutus Solutions