Hi, I have Odoo 12.0-20200916 (Community Edition) running in Windows 10.
I'm trying too add a custom field to existing view by following this tutorial
https://www.cybrosys.com/blog/adding-custom-fields-to-existing-views-in-odoo-v12

The changes does not take effect even after I restart Odoo service and upgrade the sales module on the Apps page.

These are the files that I have added or modify,
1. Added new file at Odoo12\server\odoo\addons\sale_quotation_builder\models\my_sale_order.py

# -*- coding: utf-8 -*-

from odoo import models, fields

class SaleOrder(models.Model):

_inherit = 'sale.order'

additional_note = fields.Char(string='Additional Note')

2. Added new file at Odoo12\server\odoo\addons\sale_quotation_builder\views\view_order_form_inherit.xml

<record id="view_order_form_inherit" model="ir.ui.view">

<field name="name">Sale Order Custom</field>

<field name="model">sale.order</field>

<field name="inherit_id" ref="sale.view_order_form"/>

<field name="arch" type="xml">

<field name="payment_term_id" position="after">

<field name="additional_note"/>

</field>

</field>

</record>

3. Modified Odoo12\server\odoo\addons\sale_quotation_builder\__init__.py

from . import product_template

from . import res_config_settings

# from . import sale_order

from . import my_sale_order

from . import sale_order_template

4. Modified Odoo12\server\odoo\addons\sale_quotation_builder\ __manifest__.py

{

    'name': 'Quotation Builder',

    'category': 'Sales',

    'summary': 'Build great quotation templates',

    'website': 'https://www.odoo.com/page/quote-builder',

    'version': '1.0',

    'description': "Design great quotation templates with building blocks to significantly boost your success rate.",

    'depends': ['website', 'sale_management', 'website_mail'],

    'data': [

        'data/sale_order_template_data.xml',

        'views/sale_portal_templates.xml',

        'views/sale_order_template_views.xml',

        'views/res_config_settings_views.xml',

        'views/view_order_form_inherit.xml',

    ],

    'installable': True,

}