org-hierarchical-checkbox-statistics

org-hierarchical-checkbox-statistics is a variable defined in `org-list.el'.
Its value is

t

• This variable is an alias for `org-checkbox-hierarchical-statistics'.
• This variable is obsolete since 24.4;
  use `org-checkbox-hierarchical-statistics' instead.

Documentation:
Non-nil means checkbox statistics counts only the state of direct children.
When nil, all boxes below the cookie are counted.
This can be set to nil on a per-node basis using a COOKIE_DATA property
with the word "recursive" in the value.

You can customize this variable.