Floor Structure

[nspblhs01]

I'm a newbie (architectural 2014) and had problem with Floor Structure thickness when adding the basement. I had added the basement interior/exterior walls, foundations etc, when I realized the floor structure of the basement ceiling was somehow at only 4". And I could not find anything in the manuals to tell me how it is calculated. So I gave up and deleted the Basement and then re-added the basement. The floor structure is now OK at 12 5/8".

Is there some place else I can look to find how unchangeable items such as Floor structure thickness is calculated?

Or maybe the bigger question is how do I avoid having to delete a lot of work in order to fix a problem? I knew that I may do something wrong in the basement, because it is a walkout and I really didn't know how to handle a lot of the variables and the videos and manuals were pretty poor in explaining the details.