Hi,
the original code is located in “functions.php”, but if you would like to avoid overwriting your custom changes once you update the theme, I recommend you to create a child theme and add the following function to your child theme’s “functions.php” instead of editing the original function:
function happenstance_child_new_excerpt_more( $more ) {
global $post;
return '...<br /><a class="read-more-button" href="'. esc_url( get_permalink($post->ID) ) . '">' . __( 'Read more', 'happenstance' ) . '</a>';}
add_filter( 'excerpt_more', 'happenstance_child_new_excerpt_more', 100 );
Best regards,
Tomas Toman