Comparison of pitching moment at different locations
Is it OK to compare all three moment coefficient together given that the reference points are different?

No, it's not ok. The pitching moment will be different at different reference locations, unless lift is 0.

Do I have to change the reference point to 0.25c for the two last results? if so, how can I achieve that without restarting the simulations and specifying the 0.25c as reference point?

The industry standard for reporting and comparing pitching moment is quarter chord, because the classic Thin Airfoil Theory concludes that infinitely thin airfoils in subsonic flow have their aerodynamic centres at quarter chord.
That being said, there is absolutely nothing wrong gathering the pitching moment data about any other point, as long as you stay consistent when comparing to other data (or more importantly other people's data). You can convert the pitching moment from one point (say $x_0$) to any other point ($x$) via:
$$M(x) = (L\cos\alpha+D\sin\alpha)(x-x_0) + M_0 \approx L(x-x_0) + M_0$$
where $L$ is the measured lift, $D$ is the measured drag, and $M_0$ is the measured pitching moment at $x_0$. The approximation works great at small AOA ($\alpha$).