[Pan-users] Don't want to automatically download headers

[Dr Aldo Medina]

I used to use Netscape for usenet browsing, and now I'm trying Pan.
Since I'm subscribed to several newsgroups with many post, I usually
browse them one by one, just reviewing those heads marked as new (bold).
However, Pan tends to download new headers all the time, and when I go
to some newgroups, headers new for me, are no longer marked as new,
since newer headers have already arrived (please excuse my english, I'm
not a natural english speaker, as you can see).

How can I control exactly when Pan retrieves new messages?
TIA.