account_invoice_do/view/invoice_form.xml

<?xml version="1.0"?>
<!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
this repository contains the full copyright notices and license terms. -->
<data>
    <xpath
        expr="/form/notebook/page[@id='payment']/label[@name='amount_to_pay_today']"
        position="before">
        <label name="amount_paid"/>
        <field name="amount_paid"/>
    </xpath>

    <xpath
        expr="/form/notebook/page[@id='payment']/field[@name='amount_to_pay']"
        position="after">
        <label name="due_date"/>
        <field name="due_date"/>
        <label name="days_elapsed"/>
        <field name="days_elapsed"/>
        <label name="days_overdue"/>
        <field name="days_overdue"/>
    </xpath>
</data>