We're really sorry, but there is not an easy solution for this case. You should not use the code above.  

After adding the code to reverse the order of replies so that the latest reply is on page 1 of the topic, the action, of where the user is directed to the last page after a reply, remains the same before adding the above mentioned code.

ie When someone posts, the post will show up on page 1 but the page refresh after posting redirects to page 9 (example for last page). Any suggestions on how I should be trying to fix this so they go to the first page of the topic instead of the last page after submitting?

Thanks again.

We don't follow you well. If you're asking to redirect to the last reply when the page is opened, this isn't possible.

I also recommend purchasing pro support and reaching out to the pro support team for customizations: https://wpforo.com/pro-support/#plugin-support

I've added the code to my functions file so that the latest reply will display on page one, however when a new reply is submitted the user will be redirected to the last page when I require the user to be redirected to the first page where the new reply displays.

Is there a solution for this after adding the code to reverse the post/reply order.

This is the code that I have added to my functions file based on other support topics for reversing the post/reply order.

add_filter('wpforo_post_list_args', function ($args){
    if(!empty($args)){
       $args = '`is_first_post` DESC, `created` DESC, `postid` DESC';
    }
    return $args;
 });

Thanks in advance.