Where the setting is depends on the brand of video card for the specifics, but it should be in the display settings. Right-click on the desktop. Or look in the Control Panel. If it's an AMD card, the Catalyst Control Center. AMD calls it scaling. I had the issue when I connected a computer to my TV.
It's just another methods to adjust screen size. Imagine a projector and a screen hanging on the wall. You could re-scale the image by moving the projector closer or farther from the wall so that it fits on the screen as best as possible. Software can do the same thing.
it was actually by the picture options of the TV itself, changed it from 16:9 to just scan