One method of changing currency is to allow the customer to choose. The item button code needs to be manually coded as the online button creator does not have the capability you need.
See the example below:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Button Example Code</title>
<!-- START META TAG SECTION -->
<meta charset="utf-8">
<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
<meta http-equiv="Content-Language" content="en">
<!-- END META TAG SECTION -->
</head>
<body>
<!-- START SAMPLE CODE SECTION -->
<!-- PARAGRAPH 1 -->
Currency & Country Code Examples
<br><br>
Buy Now with option for paying in a different currency.
<br><br><br>
Widget - $5.00 USD
<br><br>
<!-- Start of Buy Now Form -->
<form target="paypal" action="https://www.paypal.com/cgi-bin/webscr" method="post">
<!-- If using a Business or Company Logo Graphic, include the "cpp_header_image" variable in your View Cart code. -->
<input type="hidden" name="cpp_header_image" value="https://www.yourwebsite.com/logo.jpg">
<input type="hidden" name="cmd" value="_xclick">
<!-- Replace "business" value with your PayPal Email Address or Account ID -->
<input type="hidden" name="business" value="your @ emailaddress.com">
<input type="hidden" name="item_name" value="Widget">
<input type="hidden" name="item_number" value="W-1001">
<input type="hidden" name="amount" value="5.00">
<input type="hidden" name="no_shipping" value="2">
<!-- Replace value with the web page you want the customer to return to after a successful transaction -->
<input type="hidden" name="return" value="http://www.yourwebsite.com/ThankYou.html">
<!-- Replace value with the web page you want the customer to return to after item cancellation -->
<input type="hidden" name="cancel_return" value="http://www.yourwebsite.com/Cancel.html">
Please Select Your Currency:
<select name="currency_code">
<option value="USD" selected>U.S. Dollars</option>
<option value="CAD">Canadian Dollars</option>
<option value="GBP">Pounds Sterling</option>
<option value="JPY">Yen</option>
<option value="EUR">Euros</option>
<option value="AUD">Australian Dollars</option>
<option value="NZD">New Zealand Dollars</option>
<option value="CHF">Swiss Francs</option>
<option value="HKD">Hong Kong Dollars</option>
<option value="SGD">Singapore Dollars</option>
<option value="SEK">Swedish Kronor</option>
<option value="DKK">Danish Kroner</option>
<option value="PLN">Polish Zloty</option>
<option value="NOK">Norwegian Kroner</option>
<option value="HUF">Hungarian Forint</option>
<option value="CZK">Czech Koruna</option>
<option value="ILS">Israeli Shekels</option>
<option value="MXN">Mexican Pesos</option>
</select>
<input type="hidden" name="lc" value="US">
<input type="hidden" name="button_subtype" value="products">
<input type="hidden" name="no_note" value="0">
<input type="hidden" name="cn" value="Add special instructions to the seller:">
<input type="hidden" name="bn" value="PP-BuyNowBF:btn_buynow_LG.gif:NonHosted">
<br><br>
<input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_buynow_LG.gif" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!">
<img alt="" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1">
</form>
<!-- End of Form -->
<!-- END BUTTON EXAMPLES -->
<!-- END SAMPLE CODE SECTION -->
<br><br><br><br>
<hr align="left" width="50%" noshade>
<br><br>
NOTES:
<br>
In order to test the code, you must replace the "business" value variable with your PayPal Email Address or Account ID.
</body>
</html>
