Canon PowerShot G7 X Mark III Advanced User's Manual page 286

To edit saved settings (other than shooting mode), choose
z
the settings, and then choose
[Register settings] again. These setting details are not applied in other
shooting modes.
To reset saved settings to their defaults, choose
z
(C mode)] → [Clear settings].
To automatically update your saved settings with any changes to settings
z
that you make while shooting in
(C mode)] → [Auto update set.] → [Enable].
[Custom shooting mode (C mode)] →
mode, set [Custom shooting mode
286
, change
[Custom shooting mode