Categories

Hi,
I like this theme but there are some things that makes me considering using another theme. In the header there is a place where you can select the category. I have a couple of categories and subcategories. When pressing on that field in the header all the categories are displayed as on the same level and also the same names like for example 3 times HP, 4 times accesories, … I use the same names in different categories.
Is there a way I can make the subcategories order correctly and make it clear what a category and a subcategory is?
I would place the url here but I will not because this is something I can’t show to visitors yet.
Thanks