Hello, Juergen,
Thank you for choosing XStore as your WooCommerce WordPress theme.
Please choose multistep layout and then turn it OFF Email Field Prioritized option under XStore > Theme Option > Woocommerce (Shop) > Cart/Checkout Layout and Publish it.
Please refer to the image provided at the following link for further reference: https://postimg.cc/MMVdTnZD
we hope this will solve your issue.
Best Regards,
8Theme’s Team