I have a 898si unit and when I look at my map my boat moves as I travel then when it gets near the edge of the screen I need to push my left, right, up down arrows to keep the boat on the screen to move the map. I think the map used to move and the boat stayed in the middle of the screen. I probably set something or turned something on that changed this. Can anyone tell me how to get it back to the boat staying in the middle of the screen when I'm moving? Thanks