At the risk of sounding like an idiot, I have no idea what you mean. I've seen varying resolution on my tv depending on what I'm watching. But I've seen 1080i for many things. Not sure what native is.
Press menu on your remote, go to "Settings & Help" and then choose HDTV. Under video, what is native set to? If it's set to on, the resolution changes depending on what channel you're on. If it's set to off, the resolution stays the same and can be changed by pressing the "RES" button on the front of your receiver.