Canon EOS-1D X Mark III Advanced User's Manual page 842

Rec card, img size setting
As the display used when the <
you can specify the rear LCD panel or the screen.
: Rear LCD panel
After pressing the <
< > or <
: Screen
Pressing the <
sel.] screen (or [Movie rec quality] screen in movie recording), and then each press of
the button switches between these two screens.
OFF: Disable
Disables the <
unintended changes to the selected card or image size if the <
accidentally. Use menu screens to select cards or set the image size.
> button is pressed to select a card or set the image size,
> button, you can watch the rear LCD panel while turning the
> dial.
> button displays the [Img type/size] or [Record func+card/folder
button
> button for card selection or setting image size. This can prevent
842
> button is pressed