The template you are looking for is located in order/order-details.php
But as WooCommerce templates doesn't seem to work in your theme you can try this alternative:
add_filter('gettext', 'changes_in_thank_you', 100, 3 );
function changes_in_thank_you( $translated_text, $text, $domain ) {
if( $text === 'Order details' ) {
$translated_text = __( 'Your replacement text', $domain );
}
return $translated_text;
}
Code goes in function.php file of the active child theme (or active theme).
It should work.
To target specifically "Order received" page you can replace:
if( $text === 'Order details' ) {
by:
if( $text === 'Order details' && is_wc_endpoint_url( 'order-received' ) ) {
In WPML:
1) In "Theme and plugins localization" You can load the translatable text for "Woocommerce" plugin scanning this plugin.
2) In "String translations" you should be able to find the string 'Order details'
for the woocommerce domain and change the yranslation for your language…