As far as I can judge the Lock Resolution option under Quick Setup => Display => HDMI Mode is reversed. I am using this option to enforce the 1080P23 HDMI output mode (Auto-Resolution plus Auto-Framerate ON). This way the screen has the correct frame rate for most of my videos and won't change for actual viewings and my TV does the 4K upscaling when applicable. To my surprise enabling the Lock Resolution option will switch the display back to 1080P60 with each power cycle but turning it off will keep it locked to 1080P23 as desired. This is opposite to what was expected.