How can i change front end question post editor from rich text to simple text editor?

Regarding the change front end question post editor, please tell me detail about this issue and send me a screenshot for further checking.
– To DW Q&A plugin integration with your site, you can find here for the document guide on how to create 2 file: content-start-wrapper.php, content-end-wrapper.php.
URL: http://designwall.com/guide/dw-question-answer-plugin/#Style_integration
+ Add the following code to the  content-start-wrapper.php file:

<div class="global_content_wrapper">
    <div class="container_12 with_sidebar sidebar_left">
        <div class="grid_8 push_4">
            <div id="primary" class="content-area">
                <div id="content" class="site-content" role="main">
                    <?php if( is_page() || is_archive() ) { ?>
                    <header class="entry-header">
                        <h1 class="entry-title"><?php _e( 'Question & Answer', 'dw-focus' ); ?></h1>
                    </header>
                    <?php } ?>

+ Add the following code to the  content-end-wrapper.php file:

                </div>
            </div>
        </div>
        <div class="grid_4 pull_8">
            <div class="gbtr_aside_column">
                <?php get_sidebar('secondary'); ?>
            </div>
        </div>
    </div>
</div>

Hope this helps !