Goods receive and costing

Good day,

we have downloaded the free version, when we add a cost and then do our GRV and cost has changed it doesnt update the cost entered. When no cost has been added it also does'nt ad the cost. What would be the reason?

Do we have to purchase a package to be able to load singles as main items and then let six packs and cases subtract from main item? How do we get to this?