Please let me know the name of your theme. Or you can follow this:
1. Go to Online store -> Theme -> Edit code
2. Snippet -> product-template.liquid -> You need to find an element contains the product description and button Add to card to change position as you want.
If you can not do that, please share your site URL, so I can check and provide a solution here.
This is an accepted solution.
do you want to look like this http://prnt.sc/12wqnyl
It seems that I need to enter into your store i need to change the position of description. Can I send collaborative access to you for accessing your store for change the position of description?
can you please share your site URL and if any password then please share your site password