It's good to have you here again, Mark.
I'm joining in the thread to share additional insights about this Self-Employed concern.
The Self-Employed program doesn't have the option to close books as it doesn't have Chart of Accounts to record balances. Therefore, you can continue using it as it is without closing. The system will separate them when you pull up the reports and choosing the period you want to view.
I'm leaving the following links to help your way around QBSE:
Please post here again if you need further help with the tasks in QBSE. I'll be right here to have you here