Hi,
the same happened in our case, from your first image looks like you're talking about your cart module, but you can't set the type of quantity display for the cart in the configuration, you can only set the quantity for your product pages and product listings (which you show in your second post).
@Jerome: please correct me if I'm wrong
To change the quantity display of your cart module, you have to make a small change in your cart view by going to Display -> Views -> select your template -> select product -> and open the view cart. There on line 395 the quantity display is defined:
$this->quantityLayout = 'show_select';
You can change the quantity display by modifying the
show_select to one of the other possibilities: show_default, show_default_div, show_regrouped, show_select, show_select_price, show_simple, show_leftright, show_simplified, or show_html5.
These are the same possibilities you have for your product quantity display, you can play around with it to see which one you prefer in your cart module. Hope that helps.