How can I change the default units in the Image Size dialogue?

[darkeforce]

I have been trying to set the default units in the Photoshop CS6 Image Resize Dialogue to Percentage for a long time now. I've opened the Units Preferences and changed the Ruler measurements to percentage while I don't currently have any files open, and from what I read online, the ruler default units are what's used as the default in the Image Resize Dialogue, but every time I open it when a document is open, the units are set to Centimetres, instead of Percentage. The previous versions of Photoshop I used didn't have this problem; I could have percentage as the default units for Image Size, but it just doesn't seem to work in CS6.

[JJMack]

I do not think there are default setting for Image size.  I believe Photoshop notes the unites you used the last and the will open Images Size set to those units the next time you open Image size.  Photoshop will also record the units you used recording actions steps into the action step so the step will play correctly. Imags size does not have default settings as far as I know.