<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data>

    <record id="view_account_invoice_report_search_view_inherit" model="ir.ui.view">
        <field name="inherit_id" ref="account.view_account_invoice_report_search"/>
        <field name="model">account.invoice.report</field>
        <field name="arch" type="xml">
            <xpath expr="//filter[@string='Due Month']" position="after">
                <seperator/>
                <filter string="Sales Channel" context="{'group_by':'sales_channel_id'}"/>
            </xpath>
        </field>
    </record>

</data>
</openerp>
<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data>

    <record id="account.view_account_invoice_report_graph" model="ir.ui.view">
        <!--<field name="inherit_id" ref="account.view_account_invoice_report_graph"/>-->
        <field name="model">account.invoice.report</field>
        <field name="arch" type="xml">
             <graph string="Invoices Analysis" type="pivot">
                 <field name="sales_channel_id" type="row"/>
                 <field name="date" type="col" interval="month"/>
                 <field name="price_total" type="measure"/>
             </graph>
        </field>
    </record>

    <record id="view_account_invoice_report_search_view_inherit" model="ir.ui.view">
        <field name="inherit_id" ref="account.view_account_invoice_report_search"/>
        <field name="model">account.invoice.report</field>
        <field name="arch" type="xml">
            <xpath expr="//filter[@string='Due Month']" position="after">
                <seperator/>
                <filter string="Sales Channel" context="{'group_by':'sales_channel_id'}"/>
            </xpath>
        </field>
    </record>

</data>
</openerp>

Set sales channel report as default instead of product category
[IMP] Set sales channel report as default instead of product category
