Interesting what can be found in books...........

Center of pressure is considered to be where the lift generated acts.
Pitching moment is considered to be the lift force times the distance.
The coefficient of moment is the pitching moment reduced to be dimensionless the same way the coefficient of lift is.

The Cm of a wing changes value as the CP moves. It will decrease as the CP moves aft, as when airspeed increases. The lift remains the same, but the lessened angle of attack changes the CP aft, increasing the distance the force acts upon, and the moment decreases.

However, the lift required of the system is constant, since the airplane isn't losing weight. And when it moves aft, it obviously still works on the entire balance system of the entire airplane. What it does to the wing is interesting, but what it does to the airplane moreso.