what is "change post"?

20/04/17 17:06
hello. this seems new button when i review my team players, what is it for is there someone who knows anything - all i see is to pay 9 golden balls to change but why do it i do not understand
23/04/17 13:09
You can change a player from say a Mid to say a Forward

I cant see the point of paying 9 Gold balls when that's all you get. If you dish out the points from training as far as I can see you can more or less do that anyhow & not need to pay sod all for it