That is it.i tried the 2 on the side.I was sure they all the same. One of 2 on the back is arc so if you have a receiver you are left with one hdmi port that can handle 120hz.
Thank you very much for your help.
It does say it can work at 1440@120 hz ,there isn't an option to change refresh rate.It is connected with the brand new cable that came with the xbox to the 2.1 hdmi port.Lg claims that this is 4k uhd native 120hz tv.