Can anyone advise on this because I'm having a serious case of wtf
The manual says to Select the Video (default) input type when a PC is connected. Underneath that, it says to Select the PC input type when a PC is connected to the HDMI input terminal. (This is page 55 in the manual for what it's worth).
In Video mode, the tv Overscans so you lose the edges of the picture but the picture looks generally better and you have access to a lot more settings. In PC mode, the picture fills the screen but the settings are a small subset of what's available in the Video mode, the picture looks a little saturated colour-wise and less smooth.