I set them like fraserd123,
Middle defender: ball playing defender - marking (or if you don't have a ball plying defender set him as normal defender)
the other central defender - defend - more pressing and short passing style.
But i use half back (alex sandro - b angulo , marcos rocha - nyom right now) set: press more, tight marking. And preferred moove go forward whenever is possibile (or you can set istruction)
Middlefielder:
left: Box to box (support- shot less)
centre: central middlefielder (support - shot less)
right: advanced playmaker (attack generally, or support..depends..But you could set also as box to box or central middlefileder too