Change position to "under cart"

did so, thanks!

unfortunately nothing has changed in output.. you mind feeding me with another hint?

www.schmalys.com/bbq/original-memphis-bbq-hot-detail

Yes it's actually because the addtocart-area class is showing twice on your template.
Actually I would suggest to return to the original code and add to your virtuemart view a
div class="spacer-buy-area" /div
where you want the buttons to show (within the addtocart-area div)
What do you think ?

sounds very good.. but i fear i have no clue on how to do it.. but i am willing to learn of course..hope you are OK guiding me through the steps.

what virtuemart file should i touch?

The original file is in component/com_virtuemart/views/productdetails/tmpl/default.php

But if you have a template override for this, you'll have to edit the file at
templates/[your template name]/html/com_virtuemart/productdetails/default.php

Hope it helps.

now i added the recommended <div class="spacer-buy-area"></div> to the default.php of /templates/yoo_sun/html/mod_virtuemart_product

but it seems that I can add the <div class="spacer-buy-area"></div> anywhere without changing position in output...

if I Look at this page
www.schmalys.com/bbq/original-memphis-bbq-hot-detail
source code, I can't find any container with the 'spacer-buy-area' required class

You modified the wrong file.
if it exist, modifiy templates/yoo_sun/html/com_virtuemart/productdetails/default.php
if this one doesn't exist,

copy
component/com_virtuemart/views/productdetails/tmpl/default.php
to
templates/yoo_sun/html/com_virtuemart/productdetails/default.php
and modify htis new one.
This is the way tmeplate overrides work. It allows you to add modification and not loos these whenupgrading Virtuemart component.

As you mentioned before,
You might need to make the modification in vmUIkit which I don't know.