History is every Chat and Computer thread you have started. Use it when you remember the work but not which tab it lived in.
Search, then open the thread. It continues from the last message.
Information
Open History from the app rail.
Find it
Search by words you remember from the prompt or the reply. Filter by Chat or Computer if the list is long.
Open it
The thread is the same conversation. Send the next message. You do not duplicate it by opening it.
Start over only when the job changed
New chat is for a new job. History is for the old one.