<magento-root>/app/design/frontend/rwd/default/template/klevu/search/v2/js-init.phtml For e.g. `rwd/default` is a active theme

js-init.phtml

<?php
/** @var Mage_Core_Block_Template $this */
/** @var Klevu_Search_Helper_Config $config */
/** @var Klevu_Search_Helper_Data $helper */
?>
<?php $config = Mage::helper('klevu_search/config'); ?>
<?php $helper = Mage::helper('klevu_search'); ?>
<?php if ($config->isExtensionConfigured()): ?>
    <?php $urlRoute = 'catalogsearch/result/'; ?>
    <?php if ($config->isLandingEnabled() === 2): ?>
        <?php $urlRoute = 'search'; ?>
    <?php endif; ?>
    <?php $landingURL = Mage::getUrl($urlRoute, [
        '_secure' => Mage::app()->getFrontController()->getRequest()->isSecure(),
    ]); ?>
    <script src="https://js.klevu.com/core/v2/klevu.js"></script>
    <script type="text/javascript" id="klevu_jsmoi_enabled">
        var klevu_moi = {
            "enabled": true
        };
    </script>
    <script type="text/javascript" id="klevu_jsvars">
        if (typeof klevu_lang === "undefined") {
            var klevu_lang = '<?php echo $helper->getStoreLanguage() ?>';
        }
    </script>
    <script type="text/javascript" id="klevu_jsapikeys">
        klevu({
            "analytics": {"apiKey": "<?php echo $config->getJsApiKey() ?>"},
            "search": {"apiKey": "<?php echo $config->getJsApiKey() ?>"},
            "moi": {"apiKey": "<?php echo $config->getJsApiKey() ?>"}
        });
    </script>
    <script src="https://js.klevu.com/theme/default/v2/quick-search.js"></script>
    <script type="text/javascript">
        klevu.interactive(function () {
            var searchBoxSelector = 'input[name="q"]';
            var APIv2CloudSearchURL = "eucs31v2.ksearchnet.com"; //APIv2 Cloud Search URL, Change the value
            var options = {
                url: {
                    protocol: "https:",
                    landing: '<?php echo $landingURL;?>',
                    search: 'https://' + APIv2CloudSearchURL + '/cs/v2/search'
                },
                search: {
                    minChars: 0,
                    searchBoxSelector: searchBoxSelector + ',.kuSearchInput',
                },
                moi: {
                    active: true
                }
            };
            klevu(options);
        });
    </script>
    <?php $customerSession = Mage::getSingleton('customer/session'); ?>
    <?php $isLoggedIn = $customerSession->isLoggedIn(); ?>
    <?php if ($isLoggedIn): ?>
        <script type="text/javascript">
            var klevu_loginCustomerGroup = "<?php echo $customerSession->getCustomerGroupId(); ?>";
            var klevu_idCode = "<?php echo "enc-" . md5($customerSession->getCustomer()->getEmail()); ?>";
        </script>
    <?php endif; ?>
    <?php $currency = $helper->getCurrencyData(); ?>
    <?php if (!empty($currency)): ?>
        <script type="text/javascript">
            var klevu_currentCurrencyCode = "<?php echo Mage::app()->getStore()->getCurrentCurrencyCode(); ?>";
            var klevu_currentCurrencyRates = {<?php echo $currency;?>};
        </script>
    <?php endif; ?>
<?php endif; ?>

Replace the value for variable var APIv2CloudSearchURL available on box.klevu.com > Store Settings > APIv2 Cloud Search URL:

https://gist.github.com/sandipklevu/57372b8ee8068b5e1f0042148fa00a3e#file-js-init-phtml-L38