Have the new macbook pro with touch.. Purchased a new Ultra HD 4K LG monitor and was excited to use it as an external display..... Went to apple store in Detroit and nobody seemed to know what I need. I was advised to purchase a USB C to thunderbolt 2 dongle. (Is USB C Also called thunderbolt 3?? Is Thunderbolt 2 display port???) Either way the Monitor take a display port but not a thunderbolt 2 which is also a mini display I guess. Was also advised at apple store to not use HDMI as it wont support 4k on the monitor. I have this monitor: http://www.lg.com/us/monitors/lg-27UD68-W-4k-uhd-led-monitor can somebody please help me?? Also live 2 hours away from the store so I'm not going back - Have to purchase online.... So tempted to return this macbook pro - disappointment after disappointment.