Brief
We have modified the 'invoice_functions.php' file for release 3.4.7.
 
Description.
PDF invoice shows incorrect order prices while changing currency rate.
 
Solution.
We would recommend to download an updated version of the file from here: http://www.viart.com/downloads/invoice_functions-3.4.7.zip
 
Further, extract the above mentioned file into the 'includes' folder of your shop replacing an existing one. Don't forget to make a backup copy of the current file in case something goes wrong.