Customizing Elements: Best Selling Products and Featured Products

Hi, I have just relaunched my new site ( using one of the Themeforest themes. On the home page of the site I am featuring my best selling products but form launch the best selling seem to be randomly generated (as the site launched last night and. No sales have come through). Is there any way to manually change what products are featured in the “Best Selling” element?

Also, with the “Featured” Element, is there any way to place individual products / select the exact products that you want to feature?

Thanks for you help!