should I then copy functions.php and paste it into the child theme folder and make the change there?
due to the nature of functions.php, directly copying/pasting the full functions.php of the parent theme into the child theme would get you a lot of errors;
however, there is a possible way of changing the wording of the ‘continue reading’ link:
https://www.transformationpowertools.com/wordpress/read-more-in-twenty-ten-child-theme
– just for the records:
this would be the code in functions.php of the parent theme to edit the wording:
function twentyten_continue_reading_link() {
return ' <a href="'. get_permalink() . '">' . __( 'Continue reading <span class="meta-nav">→</span>', 'twentyten' ) . '</a>';
}
but i forgot to mention, that the wording is also in loop.php:
<?php the_content( __( 'Continue reading <span class="meta-nav">→</span>', 'twentyten' ) ); ?>
however, the above linked solution should take care of changing the ‘continue reading’ text sitewide.