org-use-fast-todo-selection

org-use-fast-todo-selection is a variable defined in `org.el'.
Its value is

t

Documentation:
Non-nil means use the fast todo selection scheme with C-c C-t.
This variable describes if and under what circumstances the cycling
mechanism for TODO keywords will be replaced by a single-key, direct
selection scheme.

When nil, fast selection is never used.

When the symbol `prefix', it will be used when `org-todo' is called
with a prefix argument, i.e. `C-u C-c C-t' in an Org-mode buffer, and
`C-u t' in an agenda buffer.

When t, fast selection is used by default. In this case, the prefix
argument forces cycling instead.

In all cases, the special interface is only used if access keys have
actually been assigned by the user, i.e. if keywords in the configuration
are followed by a letter in parenthesis, like TODO(t).

You can customize this variable.