C# accessing settings from another program

You can't access the memory of a running program from a different program (or even from a separate running instance of the same program) so unless you wrote "Program X" to expose it in some way (via a file, or a socket connection, or some other means) then you cannot access it in "Program Y".
 
Trying to access the memory of a different application is one of the main reasons for an application crashing - whether it is deliberate or not you can't access outside your own processes memory space.