When connecting Live Gamer Ultra (GC553) to my 4K TV with the input source(PlayStation/Xbox game console) I can’t select 2160p (4K) resolution at game console settings, only 1080p available, what to do?

Please ensure that you connect the 4K60 Pro to GC553 and an HDMI 2.0 on the 4K TV by using the HDMI 2.0 or above cable

Press the Menu button your TV remote, then scroll down and choose options, and Select HDMI Input Mode.
Next, choose the input mode to HDMI 2.0