Just some Doubts about where to change options

Hello,

1. Please make sure that you use latest versions of Woocommerce and XStore Core plugin.
Try to disable all the third-party plugins that do not come bundled with our theme and check if you still have the problem.
If the problem still persists then provide me temporary Dashboard and FTP access to your site and we’ll check what could be the reason for the problem. 
2. “Select options” button for variable products. To change this text you can use translation files or code in functions.php of child theme:

add_filter( 'woocommerce_product_add_to_cart_text', function( $text ) {
	global $product;
	if ( $product->is_type( 'variable' ) ) {
		$text = $product->is_purchasable() ? __( 'Custom options text', 'woocommerce' ) : __( 'Read more', 'woocommerce' );
	}
	return $text;
}, 10 );

3. It would be better to contact the plugin autor. Let us know how this works with default WC theme (Storefront) and we will try to make it the same way with our theme.

Regards