Adjusting category order

I am finding that it's almost impossible. When I move a category up or down, it may or may not move and sometimes jumps many levels. Moving one category also moves others. I can't input a numerical order number and then save the order, as you can in Joomla. This is important because my categories are an alphabetical list. Is it something I'm not getting or a glitch in the sofware?
Thhanks,
-Jim G.