Canon EOS-1D X Mark III Advanced User's Manual page 862

: Switch to Registered AF Function
As long as you hold down the button assigned to this function, you can switch AF operation
to your registered AF function. This is useful if you want to change AF characteristics during
AI Servo AF.
* 2: To access the detailed settings screen when the setting screen is displayed, press the <
button. Turn the <
[ ]. To configure function details, select an item, then press <
restored by pressing the <
Caution
Setting details for [Tracking sensitivity] and [Accel./decel. tracking] are not
applied when [Case A] is selected in [
> or < > dial to select an item, then press <
> button.
: AI Servo AF/Servo AF].
862
> to add a checkmark
>. Default settings can be
>