First way: I don't have menu "Payment follow-up" inside Accounting tab. Need I to install any other module? I have "account_accountant" module. Second way: I do this, but what entries I have to select? I have two entries for each transaction, one in the debit and one in the credit. And then, have I to do a partial conciliation or a reconciliation cancellation? Thanks!

Another way. Answer updated.

The reconciliation with bank statements works for cash pays?

In menu Bank and Cash you have both: Bank Statements and Cash Registers, works similar.

Queston 2) In the "other way", in the most cases credit != debit. So I do a partial reconcile. But the entries are still there! Only Odoo adds a "Ref of conciliation" which is a code like "A1, A2, etc". How works this? And the invoices are still "Open", not "Paid".

Ref of conciliation ... see my answer: https://www.odoo.com/forum/help-1/question/please-what-is-the-link-between-vouchers-and-invoices-in-the-tables-75860#answer-75861

Ok, moves with the same reconcile_id.name are reconciled, but still I can see there in the "Manual reconciliation" with the filter "unreconciled" and the invoice are still "open". I only want to set invoice -> "paid" in the most simple way when the payment is before the invoice...

Answer updated. I reconcilation is full and ok, invoice sate = Paid.

I have the module account_voucher. The partial reconciliation, is not a full reconciliation? I know that the invoice is paid if I do a "reconciliation with cancellation" but if I do a partial reconciliation, why not?

When you select Partial Reconcile invoice is not "Piad", only value "to pay" = 0. Your needs are waiting "Reconcile with Write-Off".

Ok. I am searching a way to automatically set the invoices paid if the customer has "balance ($)" > "total invoice ($)" and decrease the balance. Is there any way? Thanks you a lot for the patient!

The third way