Black boxes around icons on my display

Yesterday I posted a message of how my 7 year old changed my display and fortunately, that situation has been resolved. However, I still have black boxes around anything my cursor goes near, whether it is on the desktop or a webpage. For instance, the box I am typing in now has a black box around it. The black box is one that looks like a "text box", and will change to the shape of the icon or whatever the cursor is near. When I go to click "post message", a black box will be around the "post message" button. Any advise on how to solve this?

Again, TIA for your time!