subscribe-to-comments.php içerisinde bul -> 26.satır:
<input type="checkbox" name="subscribe" id="subscribe" value="subscribe" style="width: auto;" <?php if ( $checked_status ) echo 'checked="checked" '; ?>/>
değiştir:
<input type="checkbox" name="subscribe" id="subscribe" value="subscribe" style="width: auto;" checked="checked" />
budur sanırım...