org-hierarchical-todo-statistics

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

t

Documentation:
Non-nil means TODO statistics covers just direct children.
When nil, all entries in the subtree are considered.
This has only an effect if `org-provide-todo-statistics' is set.
To set this to nil for only a single subtree, use a COOKIE_DATA
property and include the word "recursive" into the value.

You can customize this variable.