[@robin-w Moderator 12 years, 7 months ago]

“Edit: That said, has anyone tried the code in the link you posted?”

I’ve just loaded it and it seems to work fine

function wpse_77441_change_time_format( $anchor, $forum_id )
{
    $last_active = get_post_meta( $forum_id, '_bbp_last_active_time', true );

    if ( empty( $last_active ) ) {
        $reply_id = bbp_get_forum_last_reply_id( $forum_id );

        if ( !empty( $reply_id ) ) {
            $last_active = get_post_field( 'post_date', $reply_id );
        } else {
            $topic_id = bbp_get_forum_last_topic_id( $forum_id );

            if ( !empty( $topic_id ) ) {
                $last_active = bbp_get_topic_last_active_time( $topic_id );
            }
        }
    }

      $date   = get_post_time( get_option( 'date_format' ), $gmt, $reply_id, true );
      $time   = get_post_time( get_option( 'time_format' ), $gmt, $reply_id, true );
      $dt = sprintf( _x( '%1$s at %2$s', 'date at time', 'bbpress' ), $date, $time );    

    $time_since = bbp_get_forum_last_active_time( $forum_id );

    return str_replace( "$time_since</a>", "$dt</a>", $anchor );
}
add_filter( 'bbp_get_forum_freshness_link', 'wpse_77441_change_time_format', 10, 2 );
add_filter( 'bbp_get_topic_freshness_link', 'wpse_77441_change_time_format', 10, 2 );