wc-change-currency-symbol.php

/**
 * Change a currency symbol.
 */
function wb_change_existing_currency_symbol( $currency_symbol, $currency ) {
	switch ( $currency ) {
		case 'AUD':
			$currency_symbol = 'AUD$';
			break;
	}
	return $currency_symbol;
}
add_filter( 'woocommerce_currency_symbol', 'wb_change_existing_currency_symbol', 10, 2 );