Why does Amazon show a different product when searching for a product?

For example, I have a product with three different types of it. Let it be chocolate dark, milk, and white. When I type dark chocolate it shows white chocolate. When I type white chocolate I see milk chocolate. When I type milk chocolate I see dark chocolate. Why am I getting these results? How can I fix it so that when I type dark chocolate I will see dark chocolate? Maybe some experienced Amazon sellers can give me some tips, please. Thanks!