In the past when I wished to skip numbers in headings I would simply bump the numbering up (right-click on the number and use "set numbering value") and it worked. Now Word 2010 inserts new headers and returns with the "skipped" numbers (for instance if I want to go from heading 5.4 to heading 5.9, and I change 5.5 to 5.9, I get an automatic 5.5, 5.6, 5.7 and 5.8 inserted). This didn't happen before and as far as I know I've changed no settings. Any advice? Is this a toggle I've accidentally tripped?

Thanks for any help.