Home Button destroys App?

Hey guys
I have an App and I want that when the User pushes the Home Button and then the Task Manager to get onto the App again, it should open where he left.
But that doesnt happen.
When the User is tapping the HomeButton OnPause and OnStop are activated, like it should. But when I go to the App with the Task Manager again He creates my first page again, because in the mainactivity he goes to OnCreate instead of OnRestart or OnResume.
So I think it will be destroyed instead of simply paused or stopped? How can I prevent this?
thank you very much