Hello, Diana Nikolova,
Thank you for contacting us and for using XStore.
1/ Please try to test how it works with the default WooCommerce theme – Storefront activated on your site.
We need to find out if the situation is caused by XStore or by something else.
2/ Please test how it works when the Advanced layout for checkout is disabled via Theme Options.
We kindly request that you provide us with the results of mentioned tests.
Kind Regards,
8theme team