Do you how that? Units always move forward in every direction so how do you mod it so a unit can also move backwards. Or are all SC units kangaroos?

Simply change the iscript. In the walking animation, detect which way the unit is facing and have the graphic turn all the way around.

So, does that apply to all directions like say for example, a unit facing forward will move backwards but if its facing down it will go backwards also?

In the walking animation, play the correct set of frames, and then turn it 180 degrees (I forget the number needed) without a wait in between. This should make the unit look like its walking backwards.

Well, I have an opposite problem. I have a unit that spins or flies backwards when it shouldnt. This results in a crash. I didnt write anything in the iscript that makes it fly backwards. It just does! Ive tried many solutions (yes, its the avenger problem) and none work at all.

Air units usually use the flingy settings... so maybe its your turn radius. I can't really tell...