Change Woocommerce Add to Cart Text to Something Else Functions.php

// To change add to cart text on single product page

add_filter( 'woocommerce_product_single_add_to_cart_text', 'woocommerce_custom_single_add_to_cart_text' ); 

function woocommerce_custom_single_add_to_cart_text() {

    return __( 'Buy Now', 'woocommerce' ); 

}

// To change add to cart text on product archives(Collection) page

add_filter( 'woocommerce_product_add_to_cart_text', 'woocommerce_custom_product_add_to_cart_text' );  

function woocommerce_custom_product_add_to_cart_text() {

    return __( 'Buy Now', 'woocommerce' );

}