[GMC Canuck]

Please correct me if I'm wrong but I will try and answer.
The axis between the lower and upper ball joint that the spindle turns on if moved out or in is camber (moving the top of the tire out or in, out for positive in for negative). This sets the angle of the tire when you go into a corner. You want a little negative camber, like a motor cycle leaning into a corner.
If you move the axis forward or back (you won't see any change on the tire) you're changing caster. Move the top back you have positive caster, forward for negative. Positive caster will pull the steering back to centre (like a shopping cart caster has massive positive caster and will always snap back to centre)