Floor Thickness on the Modify Level is missing

[titust11]

I want to create a 10"foundation cement slab. I created the level, created the room but on the "Modify Level" window the Floor Thickness doe not show up. I have no idea why. The videos on the web show that the Floor Thickness is there. I have the version 3.6 portable.
What is weird is that the upper levels have the floor thickness
Am I doing something wrong?
Thanks

[titust11]

Is this because Add Level at same elevation is missing, like in this video? https://www.youtube.com/watch?v=CiBwzTyuzS0
I don't have this feature

[titust11]

Problem fixed. It was due to the 3.6 portable version that I was using. This version is crippled, it lacks features

[Puybaret]

Even if it’s better to use the latest version, it’s not possible to modify the floor thickness of the first level in levels list.