I'm sorry for the late reply... it's a long and difficult argument to be explained.
the feature you need is ACCOUNTING/TAKINGS AND PAYMENTS but this procedure is related to the Accounting year, the chart of accounts, the bank details and some other information that have to be inserted.
It's not easy to explain all on the forum.
Try to use the feature as it is.... creating a new accounting year (2019).
I don't know, for example, how is the charts of accounts in USA...