If you perform online search in the Online Search Mode (Temporary Library), you need to save the references by using References > Copy References or the Copy to Local Library button from the toolbar. When you close the Temporary Library, all references in it will be lost.
You can quickly sort the references in Reference List Pane by clicking on a column heading. For example, click Year to sort by year. A second click will change the order of the sort from ascending to descending.