RE: Reversing a general journal entry and changing posting date
First, for accruals going forward, use the recurring journals with the reversing option. This will post your accrual and reverse on the next day. So if you year end is 12/31, you reverse automatically happens 1/1.
Now, for your current situation. The standard 'reverse journal', is going to reverse on the exact same day. I would suggest finding all the entries desired in the general ledger entries screen and opening the data in Excel. Then format another Excel file to the fields you need in your general journal, do some edits to get your data to reverse into the fields for the journal. Change your date and copy/paste into the journal. Basically, you have to manually reverse the accrual but the above steps should help with some automation.
