Go to the team edit screen and press [],X,[],L2,L1,then go down to how much money the team has and u can increase or decrease.
Cheat
u go to the the customise squead screen and than u go to player edit u go stand on atribute of a player and u press this code L1,L2,X,Square,X and if u have don this Correct than u can put everything on 99 and u can do that with every player.