The price prefix and suffix is the indicated currency located next to the price. 

Prefix and suffix are different and indicate if the currency should be placed in front or behind the price. 

Prefix is in front e.g. "kr. 200" and Suffix is behind e.g. "200 kr." 

By default the suffix is filled out, either leave it or change it to prefix if you prefer that.  
Note you have to enter a space after a prefix or before a suffix, otherwise the price and the pre- or suffix will be shown without space (e.g. "kr.200" / "200kr".)

ATTENTION: Don't fill out both pre- and suffix (e.g. "kr. 200 kr.")

Go to "Shop" and then "General" scroll down to Currency to add or change your prefix or suffix. 

The choosen method (either prefix or suffix) applies to all your products.