Y’all may be talking about NFHS (there is no such rule reference in NCAA).
So, for clarity, in NCAA, the play clock for any free kick (kickoff or free kick after a safety) is 25 seconds.
The play clock for the first scrimmage down after any free kick is 40 seconds, and starts when the ball becomes dead on the free kick down.
NCAA 3-2-4-b says that, as a default, the PC is set to 40 seconds and started when the ball is dead following the previous down (whether free kick or scrimmage down). 3-2-4-c then offers, essentially, exceptions to 3-2-4-b, and tells us when to set the play clock to 25, and that it will start on the Referee’s signal.
Robert