I'm new for Magento, I was tried to change the Default Sort Order by position in backend but didn't workout. how do i achieve that ? I already added the positions that product need to show. It did load to given position
After you set the positions of products within that category, do not forget to apply changes, hitting Save button. Before checking new positions of products at the front-end, clear cache and perform reindex.
To run reindex manually in Magento 2 you need to run command via ssh. In second part of this article there is instruction on how to do this.