Tanya is right.

You can change the size of the green circle using Ctrl+Shft+9 to make it smaller and Ctrl+Shft+0 to make it larger.

But the red and green circles don't overlap, causing gun and missle shots to fire way to high above the horizontal flight line!

And I see no way to make them overlap.

The FA18 that CS has setup and automatically installs with their program works right - the circles overlap. This delivers correct shooting height!

This must be fixed...because you have to take very steep dives to hit targets. You can't attack low because of this.  :-/