From the question view, you can change the order of the questions using the order column. You can use the up and down arrows to move individual questions, or you can type in the order numbers in the fields then click the save button in the header.
Please note that with Joomla 2.5, if you click on a column it will sort by that column, which is indicated by the following symbol.
So you can only save a new ordering if you are sorting by the ordering column. For example, if you click on the access column to sort by access, you’ll notice that the save button disappears in the ordering title.