What does automatic sync do with products?

When I import products I make corrections to titles, descriptions, attributes titles and I also select the images I want to appear on the products. I noticed that several products are returning the titles, descriptions, attributes and images as they are in AliExpress. Is the automatic synchronization of products overriding already imported products? I wish that only prices and stocks were updated and new variations be added, and also that this update occurred more than once a day.