BuddyPress.org

I want to change the time show of “2 weeks, 1 day ago” in topic&reply to specific time&date such as Dec 6,2012 8:30 am.

And i find the groups/single/forum/topic.php

And replace <?php echo sprintf( __( ‘%1$s said %2$s:’, ‘buddypress’ ), bp_get_the_topic_post_poster_name(),

bp_get_the_topic_post_time_since() ); ?>

with

<?php the_time(‘F j, Y’); ?> at <?php the_time(‘g:i a’); ?>

And it does show the time&date but isn’t correct,it  shows  the topic time&date of setting up Buddypress  instead of topic&reply.I don’t know why.And I has builded the child theme of function bp.php

Please tell me how to fix it in the child theme?I amn’t familiar with the codes,better to tell me the details,please