I have been getting very annoying, full screen ads frequently when I first swipe open my phone. Also at other times. There is also a frequent small "yo-yo" ad that drops down from the upper right. The Verizon store people have no idea where these come from. Is there an app I can delete or setting I can change to get rid of these? They are often timed to pop up just when I am selecting something and then hit the ad instead, thereby opening it. Thanks.