Edited to add - another user commented on his post that he was having a similar problem and discovered it was FIFO messing him up. 

I do have FIFO on -- but I can't turn it off! We used to use average costing and QB grossly messed up our P&L because the average cost was so off. 

We sell fuel. The price changes daily - sometimes even during the day- and QB was using an average cost for many years. We were purchasing fuel for $1.75 and QB's average cost was $.92. I need to use FIFO, but also don't want it to take forever to make invoices.