Hi David,
Are you editing a template that was first done in Excel 2007? In my experience, usually when a template is done first in a different version of excel that sort of things happen. But there is a way to lock the cell without relying on the right click in the Formatting sheet. You can do this by overriding it in the USE column in the formatting sheet.
Image may be NSFW.
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Thanks,
Bennie Jay