my screen resolution keeps changing

Hi There, I have my screen resolution set to 1920x1080 and it is the right size for me.
It keeps changing on me. I right click on my desktop and then click that i want to keep it at this point but it still changes to 800x 600. Can you help me please. I took my computer in to get fixed but they couldn't so they put a new hard drive in it free if that makes any difference. I have windows 7. I have internet 8....Thank you Carol

Have you run windows update and installed the latest drivers for the video card ?

As suggested ?

Are you clicking apply and OK after the changes ?

Don't know how to get the latest drivers for the video card or for the graphic card.
Yes i clicked apply and okay after the changes. How do I get to windows update please. thanks Carol

Windows Update finds latest drivers for your devices automatically, and if Windows Update didn't find them, you need to download your graphic card driver manually.

oh my goodness there are 151 updates.......got the computer back last summer and only hocked it up a few weeks ago.....will let you know what happens lol carol

it says never for updates....

Well, you gotta install all 151 updates, It doesn't take too much time, Unless if you see ''Windows 7 Service Pack 1'' Checked.

Did this and notice I now have internet 9 instead of internet 8. Also got 151 updates but the screen resolution still changed. I don't know if i got driver or graphic cards whatever they are. Know there was alot of updates and my computer is some fast. thanks Carol