How to mass change inventory valuation method?

Hi,

how can i mass change the inventory valuation method from moving average to FIFO as when i try to import data it keeps on saying duplicate.

Further, i would like to know how to create 2 different pricing mechanisms for same item. For eg. if i am selling to a wholesaler, this price should be charged and if i am selling to a retailer that price should be charged.

make sure you set “overwrite” as true