Ok, this is going to be a long one, but I think this will accomplish what you are wanting. Now, if you used the switchover date, it would be easier, but since you are using that, this is what I have for you.
In the Time Filter Module you created a couple of posts ago, create the following line items with the associated formulas, all formatted as Boolean:
Actual FIlter: ITEM(Time) >= PERIOD(CURRENTPERIODSTART()) - 4 AND ITEM(Time) <= PERIOD(CURRENTPERIODSTART()) where 4 is the number of prior months. You said 6, but I substituted 4 as my time settings are different than yours.
Forecast FIlter: ITEM(Time) >= PERIOD(CURRENTPERIODSTART()) AND YEAR(ITEM(Time)) = YEAR(CURRENTPERIODSTART())
Plan FIlter: YEAR(ITEM(Time)) >= YEAR(CURRENTPERIODSTART()) + 1 AND YEAR(ITEM(Time)) <= YEAR(CURRENTPERIODSTART()) + 3
Create a Fake Versions list with the following members: Actual, Budget, Forecast, Plan
Create a Version Mapping module that maps the Fake Versions to the Real Versions and fill in the Line item values to the corresponding "Real" Versions"
Create a Time by Version Filter module which is dimensionalized by Time and Versions, with one line item: Filter. The formula for the Filter is: IF Version Mapping.Fake Versions = Fake Versions.Actual THEN Time Filter.Actual FIlter ELSE IF Version Mapping.Fake Versions = Fake Versions.Budget THEN Time Filter.Budget Filter ELSE IF Version Mapping.Fake Versions = Fake Versions.Forecast THEN Time Filter.Forecast Filter ELSE Time Filter.Plan Filter
If you want the Quarters and FY to render as well, you will need to change the summary to ANY.
***Note - I don't like the formula because it is hardcoded, but that is the best I have right now
Now, in your Data module which is dimensinalized by Versions, I have different data for each Version
I apply the filter to the module. Note, the Time list has to be in the either the Rows or Columns and not in the Page Axis.
Now, only the months show up for the correct Version:
As for locking or making Actuals to be read only, I would review the documentation on DCA (Dynamic Cell Access). With that said, you can create a module, called Access Control Versions which is dimensionalized by Versions having two line items: Read and Write with both being formatted as Booleans. I used a formula for Write (Not Read) but you don't have to.
Back in your Data module, in the Blueprint, scroll to the right and select you DCA Access Read line item for Read and the Write for the Write DCA.