Hi,
That comes from an option called "Popup mode", and it is set on each product listing, which is why it changes from one menu item to another.
Edit the menu items "Grote Readers" and "Kleine Readers" and look at the HikaShop options of the menu item. You have there a "Popup mode" setting with these values :
- No popup : clicking the product opens the product page normally
- Popup only : clicking the product opens it in a popup
- Choose button only : only the "choose options" button opens a popup, the product name and image lead to the product page
- Inherit : takes the value of the configuration
Those two menu items are most probably set to "Popup only" while the others are on "Inherit" or "No popup".
If you want the same behavior everywhere, set all the menu items to "Inherit" and set the value once in the HikaShop configuration, "Display" tab, option "Popup mode". Every menu item on "Inherit" will then follow it.
And if one of your listings is a HikaShop products module and not a menu item, the module has the same "Popup mode" option in its options, so check it there too.