It seems your theme is sorting by a default configuration. How do I disable?

TEST:
1)Navigate to your demo http://demo.snstheme.com/sns-senia/index.php/
2) Click HEADER in main navigation
3) Notice that URL is http://demo.snstheme.com/sns-senia/index.php/header.html
4) Now Click on a product to view the product detail… I chose Simple Product 02
5) Once page is loaded click the back button on your browser to go back to the category page
6) The header page will load but then products will sort. Notice final URL … it adds query sting http://demo.snstheme.com/sns-senia/index.php/header.html?dir=asc&order=price

I think in your configuration you have a default sort function. Please tell me how to remove this.