Monitor shadows after custom resolution

My monitor is VGA and I have an AMD 480.

I used to have an HDMI to VGA cable but recently switched to display port to VGA cable.

After switching cables, the computer started improperly recognizing my 1080p monitor as 1360x768 so I opened the AMD radeon settings and created a custom resolution, which can be seen in the picture, however after i did this i noticed there were shadows to the right of everything, how can I fix this?