Hi,
The issue is that you're using a module in your center area in order to display the elements.
There is no option to dynamically change the title of a module since that title isn't displayed by HikaShop but by your template.
The title of a module is what you set in the title field of the module, period.
What you want instead is to use a categories listing menu item in the "menu" setting of your left module. That way, when you click on a link of the left module, the main area will display the sub categories/products via the menu item and there you can have the title of the menu item changed to the current category thanks to the "Use menu name instead of category name for the title" setting of your menu item that you can find when editing it via the menu Display>Content menus.