The sign in date just provides a default date for transaction entry. They do not affect the dates or periods to which transactions will be posted. The transactions are posted to the period specified when the transaction is entered into the batch (unless you are posting to the prior year and specifically ask that the batch be posted to the year end adjusting period).

If you want to post transactions to period 12, then make sure that period twelve is specified for the transaction. When you post to the prior year, the period 12 balances will be changed.

If you do not want to change the period twelve figures, but just the year ending numbers, then post the transactions to the year end period.

Make sense?

PS - Adagio is not like Simply Accounting or QuickBooks, where the sign in date determines the date of the g/l activity.