You can't, unless you know how to use command blocks.
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Make sure your console is connected to your TV via a HDMI cable. Without that specific cable, Minecraft will not allow split screen.
Try running it as an administrator and make sure you have the latest minecraft launcher and the latest version of java.
The super secret settings puts on shaders which are changes on how the game looks. For example, if you press it it could make your world look like its on an old tv screen or upside down. To undo that, restart minecraft.
I didn't make Minecraft.
Close minecraft and then reopen it. Repeat until working.