Go to customer accountcontroller find _welcomeCustomer method.
file location must be like app/code/core/Mage/Customer/controllers/AccountController.php
Search for protected function _successProcessRegistration(Mage_Customer_Model_Customer $customer) function at accountcontroller.php file and change following:
$url = $this->_getUrl(‘*/*/index’, array(‘_secure’ => true));
to
$url = Mage::getUrl(‘thank-you’, array(‘_secure’=>true));
OR
Search for
$successUrl = $this->_getUrl(‘*/*/index’, array(‘_secure’ => true));
replace this code with your URL
$successUrl = $this->_getUrl(‘thank-you’, array(‘_secure’ => true));
And don’t forget to create Thank You Page with URL Key as thank-you or you can change with your desired url, but need to change thank-you with same.
