This is where you need to have an understanding of how the AF modes on your camera works and the options that you have in terms of AF area modes. As you are aware, there are three AF modes on your camera. These are Auto-Focus Continuous Servo (AF-C), Auto-Focus Single Servo (AF-S) and Auto Servo Auto-Focus (AF-A). The steps that I am going to detail here will be based on the Nikon system. Your camera system is likely to be slightly difficult, but the steps are more or less common for all systems.