Our books go back to 1995.  Prior to 10/1/2011 we never used the Accounting Period feature, which is a major overisht.

So I turned on Accounting Periods on 10/1/2011, a Saturday when no one was working.  Once on, I created one Posting Period for each quarter from Q1 1995 to Q4 2011.

After creating 4 of the quarters (Q4 2010, Q1 2003, Q1 1999, and Q3 1995), NetSuite automatically assigned the respective Posting Period to all transactions dated within each of those 4 quarters.  NetSuite, however, did not touch any of the other 64 quarters.

I actually desperately need NetSuite to automatically assign Posting Periods to all transactions retroactively, but I cannot figure out how I made it happen for Q4 2010, Q1 2003, Q1 1999, and Q3 1995.