Image Thumbmail doesn’t show under the large image as per Galery Layout

I am currently have 4 Thumbmail images on left handside of the large image in the product page.
I try to have 4 Thumbmail images sitting underneath the large picture. To do so ,on the Theme settings > Single Products > Gallery > Gallery Layout, I change to the second option that have 4 thumbmail image sitting underneath the main picture.

Please assist.
Regards,