Buttons on WooCommerce pages are editable via Customizer
Archive/Shop page product button – to edit it go to Customizer – WooCommerce – Archvie/Shop – Button
Product page button – to edit it go to Customizer – WooCommerce – Product page – Button
All other WooCommerce buttons (like on cart or checkout page) can be customizer via Customizer – WooCommerce – Buttons