Ah, P.Pilcher, What I did to stop the magnifier didn't work. It's back. I don't know why it came on but at least I know how to switch it off now. Oh no I don't! I opened the box from "accessories" and the bottom little box was inexplicably ticked again. I unticked it but the magnified square is still there. I'll have to turn my computer off and go for dinner but will sign in again later in the hope of discovering pearls of wisdom here! Thank you all in advance!
Thank you also Green Granite. I'll look at that after dinner too.