woocommerce/docs/code-snippets/change-a-currency-symbol.md

Rename a country

See the currency list for reference on currency codes.

Add this code to your child theme’s functions.php file or via a plugin that allows custom functions to be added, such as the Code Snippets plugin. Avoid adding custom code directly to your parent theme’s functions.php file, as this will be wiped entirely when you update the theme.

if ( ! function_exists( 'YOUR_PREFIX_change_currency_symbol' ) ) {
  /**
   * Change a currency symbol
   * 
   * @param string $currency_symbol Existing currency symbols.
   * @param string $currency Currency code.
   * @return string $currency_symbol Updated currency symbol(s).
   */  
  function YOUR_PREFIX_change_currency_symbol( $currency_symbol, $currency ) {
    switch ( $currency ) {
      case 'AUD': $currency_symbol = 'AUD$'; break;
    }

    return $currency_symbol;       
  }
  add_filter( 'woocommerce_currency_symbol', 'YOUR_PREFIX_change_currency_symbol', 10, 2 );  
}