LG 27UD58 4K monitor with 2014 13" rMBP

[bigpoppamac31]

Okay so I just bought my first external monitor today and I'm overall very excited. I have a 2014 13" rMBP which can output 4K but only at 30Hz. I seem to be able to get 4K when using HDMI to HDMI after playing around with settings in preferences. But when using HDMI to display port (with adapter) I seem to only get 1080p on the LG display. Also brightness is maxed but I had to turn down contrast to be able to see things like the contrasting colours of grey and white in the song listing in iTunes. Otherwise it was all white. Same with websites like Facebook. The posts are white but the space around it is grey. But with high contrast it was all white. Also when on seemly 4K the cursor seems kinda sluggish. But when on 1080p it's fine. How can I adjust the settings to get the best of this display and also how can I get more aspect ratio options?

Also this came in the box.

 

[bigpoppamac31]

Okay so I figured it out. I had to hold the option key while clicking on the "scaled" button. I was misreading how to do it. Even so the other aspect ratios are displayed in "low res". For example 2560x1440 which is what I'd love to use is kinda blurry and not crisp. May be because my Mac can only do 30hz refresh. Full 3840x2160 seems clear but everything is very small. I'd never use that option. Using the monitor at 1920x1080 aspect is fine but I'd prefer 2560x1440. Maybe I need to upgrade my Mac.