How can I fix navigation issues in my online store?

I’m a newbie to Shopify but have been doing online marketing since 1994. I can’t get my store navigation to work properly. My site is https://jettison.store/. I have set up some sub menus and intend to do more but I can’t get the navigation right. Right now I have 3 sub menus under “Antiques and collectibles”, which are “paper and art”, “barware” and “kitchenware”. I can’t get any products to link to the sub menus. For example, I have two pieces, a print and an old notepad that show up under the collection antiques and collectibles. I hoped that I could associate them with the sub menu paper and art but I can’t. I setup another collection called art and paper and they show up there. What is the secret to having items being able to be indexed and searched on sub menus in the header? Thanks in advance.

It looks like the theme is called “craft”.

That was where I got it. Thanks.