Hi Raquel,
In the last Projection node of view Currency Conversion is not supported, so you can see all the fields related to currency convrsion are disabled.
If you want to apply currency conversion you should have Aggregation as the last node in view. Right click on last Projection node > Switch to Aggregation. Now all the currency conversion fields will be enabled and you can apply the currency conversion for the calculated column.
Regards,
Rashmi