Seems author of this plugin not updating for a long time. Here what need to do to work that “Update” button.
Edit this plugin in plugins admin page or in WP “/wp-content/plugins/wp-comment-auto-responder/wp-comment-auto-responder.php”.
Find this code block:
<form action="options-general.php?page=<? echo $_GET["page"]; ?>" method="post">
<p>Write your message below:</p>
<textarea name="wpcar_testmsg" id="wpcar_testmsg" cols="100%" rows="5"><? echo $_POST["wpcar_testmsg"]; ?></textarea>
<p>Destination eMail:</p>
<input name="wpcar_testto" id="wpcar_testto" value="<? echo $_POST["wpcar_testto"]; ?>" style="width:60%" />
<input class="button-primary" name="wpcar_testsbt" type="submit" value="Send Mail" />
</form>
and remove <form action="options-general.php?page=<? echo $_GET["page"]; ?>" method="post">
and also end of form tag </form>
.
This form tag is already used what is causing this conflict in some browsers.