Change position of "proceed to checkout" button

Hi!

How can I change the position of the "proceed to checkout" button to the right (see screenshot)

Best regards

It's on the right by default.
If you don't see it on the right, it means that your template's CSS overrides the CSS in HikaShop. So you should edit the hikashop CSS and change the code:
#hikashop_checkout_next_button{
float:right;
}

to:
#hikashop_checkout_next_button{
float:right !important;
}

But this button has class "input .button hikashop_cart_input_button"

Yes. The button as the class hikashop_cart_input_button and the id hikashop_checkout_next_button

Here is what I found in the source code

You should have the id after the value. If you don't, maybe it's because you edited the file step of the view checkout where the id parameter is given to the next button:
echo $this->cart->displayButton(JText::_('HIKA_NEXT'),'next',$this->params,hikashop_completeLink('checkout&task=step&step='.($this->step+1)),'if(hikashopCheckChangeForm(\'order\',\'hikashop_checkout_form\')){document.getElementById(\'hikashop_validate\').value=1; document.forms[\'hikashop_checkout_form\'].submit();} return false;','id="hikashop_checkout_next_button"');

In the file "step" of the view "checkout" there is no "proceed to checkout" button! I'm talking of the cart which is displayed above the product listing, when you added a product to the cart.

Wow sorry. I was thinking about the cart view of the checkout.
Indeed, that's not the good thing to do for what you want

You should try to add the CSS:
#hikashop_cart_module .button hikashop_cart_input_button{
float: right !important;
}

It worked with this CSS:

.hikashop_cart_input_button{
float:right;
}