exam on 1 forum abc.com
I creat 2 thread: 1 and 2
I want reply in thread 1 by user1 and thread 2 by user2
With themaposter v1.x I can choose user when add topic,But i can do it with ver 2.x
please help

See the FAQ "How to add users" (2.2) and "How to reply" (3.3): http://poster.freddy.lt/faq.php

Basically you need to specify user "rank" when adding user and select the rank when posting to post with that specific user. More detailed described in FAQ.

But when I allways use option "Load form .txt to post list" and I can't choose user post for one forum,how to setup ?

There are few ways:

1. In posts list select all posts which you want to change the rank, at the top there is a blue person icon to change the rank of all selected posts.

2. Just add this tag in the .txt file:

<user>2</user> where 2 is the number of rank. Of course the default is 1 so don't need to specify that.

I would recommend 1 since you won't need to edit .txt files and it takes few seconds.