Hello Husain Rangwala,Thank you very much for your quick help,
It works! I tried both solutions and all are OK.
With backend template I tried as follow (note for someone needs):
In Settings --> Technical --> Views
Click "Create" button to create new custom view
View Name: Footer Copyright
View Type: QWeb
Key: website.footer_copyright
Child Field:
Inherited View: Main layout
Architecture:
<?xml version="1.0"?>
<!-- Customized -->
<data inherit_id="portal.frontend_layout" name="Footer Copyright">
<xpath expr="//*[hasclass('o_footer_copyright_name')]" position="replace">
<t t-call="web.debug_icon"/>
<span class="o_footer_copyright_name mr-2">Copyright &copy; MyCompany.com</span>
</xpath>
</data>
<!--End Customized-->
=> Save
=> OK
If I try to edit from front page, it will create exact the same template in the backend view.
Thanks again,
Hung