Default speed on planning auto waypoint mission

Is there a way to change the default set 12m/s mission speed?
We have faster airframes and every planning i need to change this parameter. Always to the same 18m/s.
I searched for editable xml files in the planner folder (like the camera list) but didn’t find.
So can i change this default value in planner?

What features do you use to generate your waypoints?

I use Auto WP --> Survey grid based on a polygon.