I'm new to the Sony A7M3 and I have doing a lot of reading and watching a boatload of YouTube videos and I have a question. While watching various videos the monitor screen show the camera focusing on a subject and there is a green box in the middle of the screen. When I focus, I have a series of dots or small circles in the center of my screen. I think I would feel more comfortable with the green square. It's probably a menu choice somewhere. Any Ideas?