Oh I do have a book. I don't think I explained correctly
Book: Navigating the System
First Topic: User Preferences
New Topic: Change Password <This is the third level I want to create, and may even need a 4th later
No, I do believe I'm understanding what you want. You want this:

I had to modify that image using SnagIt.
But in order for "New Topic" to be indented, the only way I'm aware it can be achieved is by creating a new Book at the same level as User Preferences.
LIke this:

And it's been that way for as long as I've used RoboHelp. More than 20 years. Or, in all that time I've never seen anyone manage to accomplish the first scenario. 
Then again, I never claim to know all there is to know about anything. I'm always learning new things. Just this week I learned a new feature about TechSmith SnagIt that I had no clue was there. And SnagIt and I go back a long way as well! So if there's a way to make it happen, I'd love to learn about it.
Cheers... Rick 