Bought a Toshiba (exclusive Best Buy brand in the USA now) 4k Ultra HD set 55" for my office. No HDR-10 or Dolby Vision. I just wanted the biggest screen for the best price that fit on my stand and it happened to have 4k so why not tinker around with it. Comes with Chrome Cast built in. No apps.

This is from the Owners Manual:

The HDMI jacks on your TV are Ultra HD (UHD) jacks.
Depending on the UHD device you connect to the
HDMI jack or the streaming content you watch, you
may need to adjust the timing.

Mode 1
YCbCr 422/444 (supports timing limit on
Mode 2
YcbCr 420 (supports timing up to

From reading on another website i gathered Mode 1 is important for crisp text on PC at 4k/30Hz and gaming. What is Mode 2 for?
If I currently have connected to it:

1080i/720p Comcast box

1080p Amazon Fire Stick

Regular PS4

How should I set the mode for each?