Campaign Merge Fields

I have created campaign merge fields for dates in my campaign. I want to be able and go in and change these dates once each time I begin a new series. However, when I try to merge them into my email template(s), I cannot find them anywhere. Where do I get them?

Thank you!

Step 1: Click in the text where you would like to insert your campaign merge field
Step 2: Click on “Merge” in the blue tool bar
Step 3: Scroll clear to the bottom of the list and click on “Campaign Fields”
Step 4: Select from the list which of your custom merge fields to insert