I tried:
In vendor folder
<item name="grand-total" xsi:type="array">
<item name="component" xsi:type="string">Magento_Tax/js/view/checkout/cart/totals/grand-total</item>
<item name="config" xsi:type="array">
<item name="template" xsi:type="string">Magento_Tax/checkout/cart/totals/grand-total</item>
<item name="exclTaxLabel" xsi:type="string" translate="true">Order Total Excl. Tax</item>
<item name="inclTaxLabel" xsi:type="string" translate="true">Order Total Incl. Tax</item>
<item name="title" xsi:type="string" translate="true">Order Total </item>
</item>
</item>
In my module Test\MyAccount\view\frontend\layout\checkout_cart_index.xml
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceBlock name="checkout.cart.totals">
<arguments>
<argument name="jsLayout" xsi:type="array">
<item name="components" xsi:type="array">
<item name="block-totals" xsi:type="array">
<item name="children" xsi:type="array">
<item name="grand-total" xsi:type="array">
<item name="config" xsi:type="array">
<item name="title" xsi:type="string" translate="true">You Pay</item>
</item>
</item>
</item>
</item>
</item>
</argument>
</arguments>
</referenceBlock>
</body>
</page>
Best Answer
The cart summary used js layout.
In our custom layout,
app/code/Vendor/Checkout/view/frontend/layout/checkout_cart_index.xml
Tested on Magento 2.2.0 version.