Rainbow S

I recently got a new laptop and i started playing around with the background/themes and all that. Not liking this one landscape background, i changed it to something else, but when i turned my laptop on the next day, my new background suddenly transitioned back to that landscape one i didn't like. I've tried other backgrounds, i've saved my changes, but no matter what i do, it goes straight back to the ugly landscape. Is it my settings? An internal problem? Please help, thanks!

Please, please, please do not answer for the sake of gaining more points. I need real solutions and real answers, not cutesy comments like how much you like this or that. Only answer if you truly have a means of helping me. Thank you very much for being considerate!