Second screen problems (HDMI connection - dock)

[kryptonetics]

I've been trying to hook up a second monitor to my Surface and have been running into some problems. My setup is a Surface Pro 6 in a Kensington SD7000 and the monitor is hooked in through the HDMI connection. The second monitor is functional and I have been able to switch off the Surface display (which is what I want). The issue is that after setting the resolution to fill the display, the text is blurry. I can read Word documents but they aren't as clear as they should be. Is there a reason why the text is blurry?