app-odoo/app_web_fullwidth/views/res_config_settings_views.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <record id="view_app_theme_config_settings" model="ir.ui.view">
        <field name="name">res.config.settings.view.form.inherit.app_odoo_customize</field>
        <field name="model">res.config.settings</field>
        <field name="priority">20</field>
        <field name="inherit_id" ref="app_odoo_customize.view_app_theme_config_settings"/>
        <field name="arch" type="xml">
            <xpath expr="//group[@name='app_ui_internal']//group[@name='app_ui_internal_right']" position="inside">
                <label for="default_chatter_position"/>
                <div>
                    <field name="default_chatter_position" class="oe_inline"/>
                    <button string="Set All User" type="object" name="user_set_chatter_pos" class="ml4 oe_highlight"/>
                </div>
            </xpath>
        </field>
    </record>
</odoo>