Dear Thaworn Hinsui,
Please go to your_site\templates\sj_appstore_hitech\html\com_virtuemart\category\default.php and find:
<div class="addtocart-area">
<form action="index.php" class="product js-recalculate" method="post">
<?php if (!empty($product->customfieldsCart)) { ?>
<div class="product-fields" style="display:none;">
<?php
foreach ($product->customfieldsCart as $field) { ?>
<div class="product-field product-field-type-<?php echo $field->field_type ?>">
<span class="product-fields-title" ><b><?php echo JText::_($field->custom_title) ?></b></span>
<?php if ($field->custom_tip) echo JHTML::tooltip($field->custom_tip, JText::_($field->custom_title), 'tooltip.png'); ?>
<span class="product-field-display"><?php echo $field->display ?></span>
<span class="product-field-desc"><?php echo $field->custom_field_desc ?></span>
</div><br />
<?php
}
?>
</div>
<?php } ?>
<div class="addtocart-bar">
<span class="quantity-box">
</span>
<span class="cart_btn">
<input type="submit" title="<?php echo JText::_('COM_VIRTUEMART_CART_ADD_TO') ?>" value="<?php echo JText::_('COM_VIRTUEMART_CART_ADD_TO') ?>" class="addtocart-button button1" name="addtocart" />
</span>
<div class="clear"></div>
</div>
<input type="hidden" value="<?php echo $product->product_name ?>" class="pname" />
<input type="hidden" value="com_virtuemart" name="option" />
<input type="hidden" value="cart" name="view" />
<noscript><input type="hidden" name="task" value="add" /></noscript>
<input type="hidden" value="<?php echo $product->virtuemart_product_id ?>" name="virtuemart_product_id[]" />
<input type="hidden" value="<?php echo $product->virtuemart_manufacturer_id ?>" name="virtuemart_manufacturer_id" />
<input type="hidden" value="<?php echo $product->virtuemart_category_id ?>" name="virtuemart_category_id[]" />
<input type="hidden" value="1" name="quantity[]" class="quantity-input" />
</form>
<div class="clear"></div>
</div>
=>
<?php if($product->prices > 0) { ?>
<div class="addtocart-area">
<form action="index.php" class="product js-recalculate" method="post">
<?php if (!empty($product->customfieldsCart)) { ?>
<div class="product-fields" style="display:none;">
<?php
foreach ($product->customfieldsCart as $field) { ?>
<div class="product-field product-field-type-<?php echo $field->field_type ?>">
<span class="product-fields-title" ><b><?php echo JText::_($field->custom_title) ?></b></span>
<?php if ($field->custom_tip) echo JHTML::tooltip($field->custom_tip, JText::_($field->custom_title), 'tooltip.png'); ?>
<span class="product-field-display"><?php echo $field->display ?></span>
<span class="product-field-desc"><?php echo $field->custom_field_desc ?></span>
</div><br />
<?php
}
?>
</div>
<?php } ?>
<div class="addtocart-bar">
<span class="quantity-box">
</span>
<span class="cart_btn">
<input type="submit" title="<?php echo JText::_('COM_VIRTUEMART_CART_ADD_TO') ?>" value="<?php echo JText::_('COM_VIRTUEMART_CART_ADD_TO') ?>" class="addtocart-button button1" name="addtocart" />
</span>
<div class="clear"></div>
</div>
<input type="hidden" value="<?php echo $product->product_name ?>" class="pname" />
<input type="hidden" value="com_virtuemart" name="option" />
<input type="hidden" value="cart" name="view" />
<noscript><input type="hidden" name="task" value="add" /></noscript>
<input type="hidden" value="<?php echo $product->virtuemart_product_id ?>" name="virtuemart_product_id[]" />
<input type="hidden" value="<?php echo $product->virtuemart_manufacturer_id ?>" name="virtuemart_manufacturer_id" />
<input type="hidden" value="<?php echo $product->virtuemart_category_id ?>" name="virtuemart_category_id[]" />
<input type="hidden" value="1" name="quantity[]" class="quantity-input" />
</form>
<div class="clear"></div>
</div>
<?php } ?>
Thanks