I learned that when Switchover is enabled by selecting a time period from the dropdown list, Anaplan will merge data from the Actual version prior to the Switchover period with data from the Forecast version for the rest of the fiscal year.
So by changing data from forecast to actual on the forecast version, what is happen as merit of end user?
Switch is generally used in conjunction with Formula Scope, to allow a formula up until the Current Period and allow user input for the periods after current period (Switch over period here should be same as current period).
It can also be used, as you observed to combine actual data with the forecast data in the version marked as 'Current' in the model
SWITCHOVER is linked to the versions within the model and enables the model builder to allocate actual results to that version.
Example - A full year has 12 periods. The current period is Period 3 and the user would like to create a new forecast to reflect changes in the business and the competitive environment. In business change is constant and organisations must make plans to reflect this. When creating this new forecast the model builder can turn on SWITCHOVER and select period 4 as the switchover period.
As the model builder creates the new forecast in this new version values upto period 3 will pull from the ACTUAL version while values from period 4 will SWITCHOVER to the new forecast version.
It is used to ensure that the new forecast includes actual data for those periods that have passed as a forecast can no longer be created for these periods as actuals are known.