Hi Wizards,
To change the default report into another one, you can make change in the original code or you can do it by a custom module,
if you are looking to change it by custom module then you can do it as follows, you can mention the new report name at
<field name="report_name">module_name.report_id</field>
<record id="point_of_sale.pos_invoice_report" model="ir.actions.report.xml">
<field name="name">Invoice</field>
<field name="model">pos.order</field>
<field name="report_type">qweb-pdf</field>
<field name="report_name">module_name.report_id</field>
</record>
if you are going to do it in original code, then point of sale -> views -> point_of_sale_report.xml then you can change the record in the id "pos_invoice_report" like this.
<record id="pos_invoice_report" model="ir.actions.report.xml">
<field name="name">Invoice</field>
<field name="model">pos.order</field>
<field name="report_type">qweb-pdf</field>
<field name="report_name">module_name.report_id</field>
</record>