article order automatic

Hey there, im new in this wordpress forum. I have the following problem. In my new wordpress blog, using a eleganttheme, the order of articles is automatic. I want to choose by myself the order, so i edited the data of the articles to have my personal order for the last articles section. But the problem is, that some ours after, the order gets destroyed by the system. So that articles with older data get a new data, so that they are ordered before the newest articles. Does anyone know about such a problem and how to resolve it. Thnx for any help – Alex 🙂