It is not possible to change objects in a list with the change list activity. You should create a loop that iterates over the list. Place one change object activity in the loop and change the iterator. This will change all the objects in your list. Best practice is to commit outside of the loop.
Regarding your scheduled event, when you are running locally you should activate it by checking the active checkbox within the modeler. When running in the cloud or on premises you should enable the scheduled events in your settings.
The cleanest way to do this is probably through a Java action: in Java you can iterate over your enumeration and that results in the most maintainable solution.
In other projects, I've created such a solution in microflows. You can see it in this model share.
Since enumeration can only change during design time, you can run this microflow in a After Startup action: once the server has started, this list is fixed.