Changing Font Size in Keynote 6

I finally stopped dragging my feet and upgraded from Keynote '09 to Keynote 6. The first thing that I've noticed is that I can no longer select a text box of bullets with sub-bullets and click the "smaller" or "bigger" button and have the text scale up or down proportionately.

I tend to build my master slides with the main bullet at one font size, then the first level sub-bullet underneath that is slightly smaller, with the next level smaller yet and so on. When revising slides, I used to be able to just select the whole text box and click the "smaller" or "bigger" buttons to resize all of the text proportionately until it looked the way I wanted. Now, when I try this, it immediately resizes all text to the same size - usually taking on the size of the main bullet.

I find it hard to believe that my only option is resizing line by line, but I can't find any information on this anywhere...

Anyone else run into this?

Thanks, in advance, for your help.