Try adding one more attribute in get_topics() and get_posts() functions. Open this file:

/wpforo/wpf-includes/integration/ultimate-member.php

Find all this rows:

'userid' => $user_id,

Add one more row below for all of them:

'userid' => $user_id,
'orderby' => 'modified',

Thanks @robert,

Seems to work for the most part, but this function (replies) seems to have little effect

 function um_user_replies( $args ) {
$user_id = um_user('ID');
if(isset($_GET['wpfpaged']) && intval($_GET['wpfpaged'])) $paged = intval($_GET['wpfpaged']);
$paged = (isset($paged) && $paged) ? $paged : 1;
$args = array(
'offset' => ($paged - 1) * WPF()->post->options['posts_per_page'],
'row_count' => WPF()->post->options['posts_per_page'],
'userid' => $user_id,
'orderby' => 'modified',
'check_private' => true
);

For the replies function please use this:

'userid' => $user_id,
'orderby' => '`created` DESC',

Works great @robert. Thanks