Editing a scenario
To edit a scenario in a project, make it active and make the necessary changes. To save the changes, use the 
button on the control panel or File | Save ...
In Fenix+ General Settings you can turn on Automatic Save and specify the time interval at which the program will save changes.
Editing a scenario component
Scenarios in Fenix+ could use a component (topological, fire, evacuation) already in use in other scenarios. You can edit a component for multiple scenarios at once, or just for one specific scenario. This is controlled via the pop-up window, showing up when you are trying to edit the component:
Click Yes to apply all future changes only to the current scenario. In this case, a new component (different from the one used in other scenarios) will be automatically created for the current scenario.
Click No to apply all future changes to all scenarios that use this component. In this case, no new component will be created.
Additional explanation could be found in our tutorial on the topic, Scenarios in Fenix+.