To do this, choose the Status option under the View dropdown in the Keylight settings. The first step to improving your key is viewing it in a different way.
Try to get as close to your subject as possible while still selecting the color and not the subject. Move your mouse to the color you want to key out and click.
This will mask out the extraneous parts of your shot. This is a mask that is big enough to contain our subject but small enough to remove parts of the shot you want to get rid of. To get rid of this, create a garbage matte around the subject. Your shot will often have objects on the edge of the frame you want to remove such as lights or stands. Often times a green screen shot will not make use of the entire frame. You should now see Keylight listed along with it’s settings. Now select your footage and open the Effect Controls panel. Select Keylight 1.2 and drag it to your footage. Then go to the Effects & Presets panel and search for Keylight.