Calendar app not displaying by month any more

My calendar app always displayed by month, but suddenly it is only showing the days of the current week along the top of the screen EVEN THOUGH THE MONTH ICON IS SELECTED. The rest of the screen is available for entering many items in the Agenda. Before, I had the whole month showing above and a smaller rest of the screen for showing appointments. This suited me fine, but I can't get it to go back to how it was, even though I have rebooted.