Changes in module setups take effect on the date changed.  There is no way to recalculate the data in history, according to a changed setup option.  You may need to write a custom report from AR Invoice History Detail and Header to get historical information. 

Didn't there use to be a hidden utility in the *util to recalc sales history? Is it no longer there?

The only thing that comes to mind for me is the old 3rd party enhancement for recalculating AR history, and I thought that just did the By Period tables (after a fiscal year change).  I don't know if it could recalculate SO_SalesHistory.

What if I did: 

begin transaction
;with _newbalance as (SELECT
Customerno,
Year(InvoiceDate) as FiscalYear,
Month(InvoiceDate) as FiscalMonth,
sum(TaxableSalesAmt+NonTaxableSalesAmt) DollarsSold
FROM [dbo].[AR_InvoiceHistoryHeader]
Group by Customerno, Year(InvoiceDate), Month(InvoiceDate)
)
Update SH set [DollarsSold] = isnull(_newbalance.[DollarsSold],0.00)
FROM [dbo].[AR_CustomerSalesHistory] SH
left join _newbalance on SH.CustomerNo = _newbalance.CustomerNo
and SH.FiscalYear = _newbalance.FiscalYear
and SH.FiscalPeriod = _newbalance.FiscalMonth
rollback transaction

Are you trying to do the summary table update yourself?  I'm not going to comment on that, other than to say: test, test, test... before making any changes to the Live company.

Using Invoice date for Period calculations won't work if your fiscal years don't align with calendar months.

If there is no utility to do the work for me, I have to do it manually. Our reporting as-is is wrong and doesn't match. Fiscal years/ calendars all match up.

Custom Report to the raw Invoice History data is always an option.

That's what I've done, but the #s there don't match the screen on AR...causing doubt, arguments, and re-explaining every month.