On the FM3 in the Drive block Tone page you have a 3 way selector for Graphic EQ which is switchable from OFF, PRE, and POST.
On FM3-Edit you can only choose between OFF and ON, and ON switches the FM3 to PRE. You can set it to POST on the FM3 and it'll show as ON in FM3-Edit, but toggling on FM3 Edit will move it back to OFF then PRE.
On FM3-Edit you can only choose between OFF and ON, and ON switches the FM3 to PRE. You can set it to POST on the FM3 and it'll show as ON in FM3-Edit, but toggling on FM3 Edit will move it back to OFF then PRE.