Cookie management confusion

I try to manage the number of cookies I have to receive, to accept only 
those that offer me a service while rejecting all those that are only 
there to spy on me. My default setting is "Never accept cookies" and I

edit that preference for individual sites, to "Accept only cookies from 
the site I visit" if I can, or "Accept cookies" if I must.

My problem is that I would like to have my name and email automatically 
appear in the comments boxes of the various Typepad blogs I read. But 
although I have tried a number of combinations of accepting cookies from 
typepad.com and accepting cookies from the individual blogs, my details 
are always wiped and I must enter them again.

What am I missing? I feel that I still don't understand what "Accept 
only cookies from the site I visit" actually means, and how it differs 
from "Accept all cookies".
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