Change currency when selected in dropdownlist (conditional formatting) and more

First of all, i work in a dutch version of excel, but i have uploaded examples before and have never had complaints that this doesn't work for people whom use the english version (maybe it translates the functions, i simply do not know). I would upload this in a dutch part of this forum, but there doesnt seem to be one for Excel 2007.

I have made conditional formatting that changes the currency symbol when i select it in a dropdownlist (cost sheet).
If i change from EUR to USD this works (also the other way around), but only the first time. So i cant select USD then decide it should be EUR afterall, because then suddenly it doesn´t seem to work. If i ''reset the 'condit format' this will work again, but only for one time'.

I have also got 2 price table´s (cost sheet) one for EUR and one for USD (usd draws data from the EUR table and multiplies it with the exchange rate).

I have tried to create a IF function that should (in the quotation sheet)
IF (EUR = true : draw it from the eur table, and if not true draw it from the USD table. But for some reason this does not seem to work.

If anyone could help me out with either of these problems, that would be greatly appreciated.