There is more than one way to assign products to categories.
To assign products to a category from the Categories Batch List, from the batch list page, click the category you want to assign products to.
On the Edit Category Page that opens, click the Products tab.
In the products tab, click the slider in the assigned column, next to the products you wish to assign to the category you are working on.
You can also assign products to categories from a product’s page.
Select the Product you wish to assign from the Catalog Batch List. Then, on the product page, click the Categories tab.
In the categories tab, click the slider in the assigned column, next to the category you wish the product to be assigned to.
You can also add and update Categories from a CSV import, as well as assign products to categories via import.