MacBook Pro External display problem

[Pascal lai]

I just recently bought a Dell u2518d for my late 2016 macbook pro for an external monitor, however i ran into a few issues, first the monitor should be 1440p but i can only choose 2048x1080, what looks to me is the picture just zooms in, where the second problems comes which is all the text looks blurry, the last issue is that side black bars appears on youtube video, even worst on netflix where there are bar all sides. Please help, Thanks.

[Glenwing]

You need to use DisplayPort, not HDMI.

[Pascal lai]

Thanks