C#.net 2008 debug/relase

Question

I am working with a C#.net 2008 desktop application. I am wondering if you can tell me the following:
 1. How are the configuration manager (app.con.fig), "App1.exe.config", and "App1.vshost.exe.config" affect each other?
 2. If I make a change in one of these files, how do I keep the change from occuring in the other file?