Music on Hold files play according to the order in which they appear in the Music on Hold page, starting with the top file on the page, if the randomization setting is not selected. To change the order in which files are played:
On the left side of the Music on Hold page, hover your mouse over the up/down arrows for the file that you want to move (the pointer changes to a 4-headed arrow).
Hold down your mouse button, drag the file to the desired location, and then release the mouse button. A message tells you that the file has been reprioritized and prompts you to click Save.