I think it's press menu twice to get to the main tabs at the top, select sonar and scroll down, should be an option for SI range lines on or off. I think you're looking for the range lines like 20', 40', etc?
Or, if you are looking for how far out you want to be seeing returns from, from the SI screen, menu once to bring up the SI menu and you can change how far out you'll be looking left and right.