Variation Question and not able to see the Product image change

Hello!

Sorry but still i have some trouble to understand few things:

1) Im not able to see the Product Image Change also if i setup correctly the image in the Attribute (for example) and correctly setup on the dropdown menu ; this wont change on the main product image.

2) I have some trouble also to understand how to see the price while click on the variation on the product page.
For example i setup the Attribute and create 2 variations with different price stocks etc…while click on the product page nothing change on the price.

Thank you!