I currently have Batch (FY20) and Next Year (FY21). We did not post our FY19 Auditor closing entries. We need to do this before sending our FY20 TB's to Auditors.
How does one do this?

Enter the batch in Batch, using period 12 and 12/31/2019 (assuming a calendar year). It will complain that the date is wrong, but it's just a warning. Continue anyway.

When you enter the batch, do NOT use the retained earnings account, use the regular income and expense accounts. It's good form to use multiple entries in the batch, one for each AJE.

Then select Post | To Prior Year. Make sure not to select any other batches (best to make a backup first). If you want you can post the AJE's to a special period (I call it period 13) which can be included or excluded on the financials at your discretion. Posting to prior year automatically closes the P&L accounts to retained earnings.

Steve