Some variables relevant for moving and selecting articles:
nil. Gnus will then fetch the article from the server and display it in the article buffer.
nil. If you would like each article to be saved in the Agent as you read it, putting
gnus-agent-fetch-selected-articleon this hook will do so.
gnus-summary-mark-read-and-unread-as-read, and will change the mark of almost any article you read to
gnus-read-mark. The only articles not affected by this function are ticked, dormant, and expirable articles. If you'd instead like to just have unread articles marked as read, you can use
gnus-summary-mark-unread-as-readinstead. It will leave marks like
gnus-del-mark(and so on) alone.