Renaming categories (Q Mac)

I have used HOUSEHOLD:Groceries:Dining and HOUSEHOLD:Groceries since I started using Quicken in 2005. The problem with those categories is that if I search on Groceries, I also get our dining expense. So I would want to change to HOUSEHOLD:Dining and keep the category of HOUSEHOLD:Groceries. I assume there must be a way to rename HOUSEHOLD:Groceries:Dining to just HOUSEHOLD:Dining. And I want to have it take effect for all dates. Thanks for your help.