Canon EOS REBEL T8i Advanced User's Manual page 65

Quick Control Dial
(1) After pressing a button, turn the <
When you press a button such as <
selectable for approx. 6 sec. (
the setting.
When the timer ends or if you press the shutter button halfway, the camera will go back to
shooting standby.
Used for operations such as selection of the AF area, AF point, or AF operation, or the
ISO speed, drive mode, white balance, or Picture Style.
Note
Can be used even when the multi-function lock is engaged (
> dial.
> or < >, the respective function remains
). During this time, you can turn the <
65
> dial to adjust
).