ball rotation, forces and physics

I have a sphere (actor) on a plane as my platform. I created sensors for up,down,left right . I get the forces correct at the start of the game but as the sphere moves around i notice up is nolonger up, same with other directions. Where as the directions do work properly from the first movement but only change as i roll around.

Can somebody explain to me what might be going on, when i push up i want it to always move in the same direction.

The L button in the motion actuator determines whether the force is applied local or world. You want world.

I found the l button, depressed it and my problem is solved.

Thanks so much for the help