Large pdf files divisions?

I'm about to join premium and as the subject says I was wondering if you can divide a, say 40 pages long, .tns document into several problems to facilitate navigating the file.
Sorry if this is in the FAQ or somewhere else, I couldn't find anything. I tried with a 10 page long one but when I add a problem (Menu->Insert Problem), this is below all pages and cannot find a way to move them in it.
Thanks in advance.
Sorry if this is in the FAQ or somewhere else, I couldn't find anything. I tried with a 10 page long one but when I add a problem (Menu->Insert Problem), this is below all pages and cannot find a way to move them in it.
Thanks in advance.