When generating reports you may find that the drop down lists can be quite long, and often too long to to show in the standard drop down window as shown below.
While it's possible to scroll through the list to select what specifically what you want (if you don't need to use Select All), in can be quite fiddly, and you may have to scroll up and down a bit. Fortunately there's a much easier way. You will notice there is a marked corner on the bottom right of the window. This signifies that this window is adjustable, and by clicking and dragging this corner, the window can resized to show the whole drop down list as can be seen below.