We have debtors who owed us money in the last financial year in June, not on QB, however paid us in the new financial year in July, where do we put these transactions?

It depends on whether you want to record the transaction in the current financial year or the previous fiscal year, Reuben.
 

If your books from the previous year are closed, you can record it in the new fiscal year. To ensure you're handling this correctly, I recommend consulting your accountant for guidance on which specific account to use for recording the money paid by the debtor.

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