Base Currency checked off in Order Entry

Good afternoon,
We are on Vantage 8.03.410.
Our company uses multi-currency, and at the top of the order entry screen, there is a "BASE" checkbox.  If you check it off and enter your items in the line detail, it will convert the item price to an incorrect amount (takes the item price entered at base and divides it by the current exchange rate).  Per our order entry clerk, this checkbox gets checked off on its own.  Whether this is true or not, it causes nothing but problems. 
My question:  Is there any way to disable this?  When I go into customization or personalization, I can't select this checkbox in order to do anything with it.
Thanks a lot in advance for any help.
Kerry Travis, CPA, CGA
International Name Plate Supplies Limited