I changed both the lock date and the set period. These changes caused changes in all balances as seen in the Summary tab. When I changed both the lock date and set period back to what it was, the bank account balances do not return to what they were. Please advise. Thank you.
Changing the lock date should have no impact on any balance. This only prevents alteration of historical entries.
Changing the period can produce many results, because there are several options. Two things to verify:
Be sure you did not change between accrual and cash basis accounting.
Be sure you restored the same beginning and end dates of the summary period. The normal approach is to select the tick box to “Show balances for specified period,” then set the period from the first day of the current accounting period until “Today.” That way, the income and expense figures will be up to date for the current accounting period. If you originally had not set up the period, you were viewing your entire accounting record from the time you first began using Manager.
In Manager, if you do something and then undo that thing, you come back to the original result.
Not to mention, as @Tut says lock date will never have any effect on your figures anywhere.