Restaurant Theme Home Page Search Block

Hello,
I am using the directory theme with the restaurant child theme. On the home page, it presents as a large image (forks) with a search box for a keyword and then a category over the top of the image.
I would like to customise the search box to enable it to search by country and then by another category.
Where do I change this? I think it is associated with Page Setup – Home Page – Search Style 3, but I simply can’t work out how to change the search boxes. I’ve also tried using the Advanced Search functions, but they don’t seem to work either – even if you specify that they should display on the home page.
Any help would be appreciated.