Change add to cart text

add_to_cart.php

// To change add to cart text on single product page.
add_filter( 'woocommerce_product_single_add_to_cart_text', 'custom_add_to_cart_callback' );

// To change add to cart text on product archives(Collection) page.
add_filter( 'woocommerce_product_add_to_cart_text', 'custom_add_to_cart_callback' );  

// Custom add_to_cart text to change to. 
function custom_add_to_cart_callback() {
    return __( 'Submit Payment', 'text-domain' );
}