Sorry, ZAR is not a currency we have built into Hub. We currently support USD, EUR, CAD, GBP, AUD, NZD, CHF, INR, BRL, PLN. If you want to change away from the default of USD to any of the others you go to Settings > (scroll down) > Currency.

You may also want to look through some other Base answers to see why it's usually a better idea to keep your currency set to USD.