HI,
I am going to give you the tutorial based on default.php (for flexv2.php, you are going to follow the same procedure).
Open this PHP:
ROOT/templates/<yourjoomlatemplate>/html/com_virtuemart/productdetails/default.php
and find this these lines (620th):
<?php if (!empty($this->product->customfieldsSorted['ontop'])) { ?>
<li><a href="#" rel="SpecificationsBottom"><span><?php echo $params->get('productdetails_specs','Specifications'); ?></span></a></li>
<?php } ?>
CUT these codes and paste them to 725th line, Right before:
<?php if ($this->showReview) {?>
Then go back to 641th line and CUT these lines:
<?php
if (!empty($this->product->customfieldsSorted['ontop'])) { ?>
<div id="SpecificationsBottom" class="tabcontent">
<?php $this->position='ontop';
echo $this->loadTemplate('customfields'); ?>
<div class="clear"></div>
</div>
<?php } // Product Custom ontop end
?>
and PASTE them to 826th line (right before)
<?php // Customer Reviews
if($this->showReview) { ?>
And the "SPECIFICATIONS" tab will be at the footer section, and right before the RATING tab.