Hi,
It is all about your Virtuemart Configuration.
if you go to VM backend, then currencies. Just select the currency you wish to edit, then at the bottom you set it out such as For Positive or Negative Format, use {sign} for the algebraic sign, {number} for the value and {symbol} for the currency
so for instance, your default would be {number} {symbol}, just change it to {symbol} {number}
Cheers.