For most themes, simply choosing the display position option "Below "Add to cart" Button" will place the bar under the button.
If you have a Countdown Timer Bar displaying at the top of your page and you create a second bar that you would like to display underneath the Add To Cart button, you'll need to set targeting filters in order for the second bar to be displayed.
Only one timer can be displayed per page, and if a top bar is activated, it will take precedence over the other bar.
The solution is simple enough. In the timer bar that is to be displayed under the Add To Cart button:
1. Scroll down to the Targeting Configuration section
2. Under Page Targeting - display on page, select the 4th option
3. Type in "products" as the keyword
All product pages have the keyword "products" in their URL, so this will cause this timer to show when you are on a product page, while on other pages, the top timer bar will be displayed.