dotted lines around desktop icons

I see dotted square lines around my desktop i cons I hit the tab bar. Do i have to do that every time. is there a way to stop them fro coming up all the time? I am on windows 10 home in the last few weeks i had a tech work on my computer and have had these what you and some might consider minor are not to me. If he comes back even if he does nothing but look at it and move something he charges me i can not afford him this month. Is there an easier free way to do this please if you can i would be very grateful to you Thank yo in advance but i hope you can help.