How can i turn a invoice to a statement for a client?

Hi there, mark155.

I suggest going to the Customers page to convert the client's invoice to a statement.

Here's how:

1. Click the Sales menu at the left panel. Then, choose the Customers tab.
2. Select the checkboxes for the customer or customers you want to make statements for.
3. Go to the Batch actions drop-down arrow. Then, select Create statements.
4. Choose the type of statement you'd like to make in the Statement Type drop-down list. 

• Balance Forward: A list of invoices and payments with balance for the date range selected.
• Open Item: A list of open, unpaid invoices from the last 365 days.
• Transaction Statement: A list of transactions between the selected dates

      5. Fill in the date fields and hit Apply.

      6. Click Save, Save and close, Save and send, or Print or Preview.

For additional information, you check this article: Create and view customer statements. This also provides details on how you can view or customize your statements.

Please check this article to see the different definitions of an invoice, sales receipt, bill, and statement so you can properly enter these transactions in QBO: What is the difference between an invoice, sales receipt, bill, and statement?

Please know that you're always welcome to post if you have any other concerns. Wishing you and your business continued success.