Cell padding / margins (Word 2010)

Hi all, I'm pulling my hair out with this one!

I'm trying to print some simple business cards onto pre-perforated stock. I have set up a new template with the 'label' dimensions, and of course, the text aligns with the exact edge of each card. I want to add a suitable margin within each cell.

All the responses I've found simply point towards Table Tools > Layout > Cell Margins. Trouble is, when I change anything here, Word appears to accomplish the change by shifting the blue table grid - the text actually remains in the same place relative to the page! What I need is for the blue grid to stay in the same place and for the text to shift.

I've tried creating a new document etc and I always get the same result. Any ideas?

Perfect, thank you!