To change the address format (so that the postcode comes before the place), go to:
admin -> "Settings & Design" -> "Allowed countries"
and look up the country you want to change the format in.
Click "Change" and select "5" in the "Address Format" menu.
Read this if the instructions above are not correct in your store
To change the address format (so that the postal code comes before the city), go to admin -> Places / Taxes -> Countries and look up the country you want to change the format of. Click edit / select and select 5 in the Address Format menu.