Image Styles and Effects Once I've created different Effects under Image styles. How do I flip between them in the Manage Display/Manage Fields windows for the content type?

I can't figure it out.

Or am I just meant to create Different Image styles for each different effect I might like to use?
The display formatter for an image on "Manage Display" allows you to select which image style to use.

The image style itself contains the relevant effect(s)