You need edit include\staff\ticket-view.inc.php
From:
<option value="0" selected="selected"><?php echo __('Select a canned response');?></option>
<option value='original'><?php echo __('Original Message'); ?></option>
To:
<option value="0"><?php echo __('Select a canned response');?></option>
<option value='original' selected="selected"><?php echo __('Original Message'); ?></option>