Only 3 Products on Frontend

Hi,

First, please understand that we don't speak German so it's really hard to understand where these settings come from.
It seems that you might be looking at the default settings in the HikaShop configuration, which are used when you create new menus and modules.
However, if you want to change the amount of elements on a menu item, you need to edit the menu item via the Joomla menu manager and change that under the "categories options" or "products options" tab there. Just increase the number of columns and/or rows.
Also, if the number of elements which can be displayed is greater than the number of elements to be displayed on a page of the menu item, then a pagination should appear at the bottom of the listing, unless you've turned off the "pagination" setting of the HikaShop configuration, or your template has some view overrides which removes it. So check that setting and also try to display that page with the default template of Joomla.
Finally, it could also be that the way you configured the other settings of your menu item, only 3 items are to be displayed. For example, if you've selected a category where you only have 3 products in the "main category" setting of the menu item, or if you've activated the "only discounted products" setting and that only these 3 products have a discount.