Each time you create a 
Scenario you will need to add the attributes you would like to model. This post will cover how to add or remove a 
Property from a Scenario.
Under Properties you can see which Properties are included in your Scenario as well as which ones can be added.
To add a Property to your Scenario, click the 
Add icon.
To remove a Property from a Scenario, click the 
Remove icon.
Properties
If you want to read more about Properties, consider reading these additional blog posts.