Razer Raptor 144hz

I recently set it up and everything works fine and everything checks out but I cant seem to get the monitor to fill up the whole screen no matter what resolution I use. It's my first time using two monitors so I'm not very sure what the issue is or if I'm doing something wrong. Please help D: I eventually want to get a second one because of the bezel-ess look but at this rate it won't ever be because I can't seem to figure out why its not filing the entire screen.