Hello,
Please add this code in custom.css file:

.header-top-variant5, .header-top-variant5 .container {
background: #007dc3;
}

How to create custom.css you can watch in this tutorial.
Regards,
Brian Johnson.

Please, provide us access to your wp admin panel in private content.

WooCommerce 2.1.7 and Xmarket 1.7 installed on our demo and you can check that everything is working.
Maybe WooCommerce in your site updated incorrect? Or you use additional plugins?
It seems that you use cache plugin. Try to deactivate this plugin before updating.

Hello,

we check your site, everything is working good.

Hello, @zelenotosr

We fixed this issue with translation, please check your site now.
We changed code in file wp-content/themes/xmarket/woocommerce/archive-product.php in line 86 from
<?php _e( 'No products found which match your selection.','woocommerce'); ?>
to
<?php _e( 'No products found which match your selection.',ETHEME_DOMAIN); ?>

After that we updated translation files.

Hello, @kkachi514

Unfortunately, WordPress doesn’t have such feature.

Hello,

It is standard feature of WooCommerce plugin. If customer haven’t chosen any options, “Add to cart” button hidden. If you want to show this button by default, you can choose options in product by default. and these options will show in page immediately after loading.

Hello, @agencia-andante

You should upload Size guide in theme options. Navigate to WP Admin Panel -> Blanco -> Single Product page -> Size Guide img. After that, navigate to product -> edit -> Custom Settings -> Enable Size Guide on this product.

SKU you should add in Admin panel -> Products -> Edit product -> General -> SKU.

If it will not help, provide us link to your site and access to admin panel in Private Content.

Hello, @surmodernite

You should remove part of script. Navigate to this folder via FTP: wp-content/themes/blanco/js and find file script.js. You should remove next code from this file(it is approximately 276 line):

            if(jQuery('.categories-group.opened').length > 0) {
                //jQuery('.categories-group.has-subnav').addClass('opened');
            }else{
                // If doesnt exitst opened point
                jQuery('.categories-group.has-subnav:first').addClass('opened').find('ul').show();
            }

Hello,

Please, provide us access to your WP admin panel in Private Content, we’ll check it.

Prices template related with WooCommerce plugin.
You can find template of prices in this way: wp-content\plugins\woocommerce\templates\single-product\price.php