I can create a newmode in display settings, but when I attempt to add the newly created mode to VGA, VGA1 or VGA-1, an error of output VGA, VGA1 or VGA-1 not found, is returned. How do I solve this problem?
By running xrandr you should see the connected monitors output with it's default resolution.
It could by something else than the outputs that you tried.
For further info about how to add the resolution or how to make it permanent, check this post!.