The default currency represents the price set on your website for your products and services. The default currency is displayed to your website visitors who are visiting the website for the first time, so you should carefully edit it.
Step 1: Login to PrestaShop Admin Panel
Step 2: Navigate to Localization => Currencies
Step 3: From the drop down you can select the currency option and click on save.
Refresh your website in the browser to check the new default currency.