Hi,

You're looking to change the layout of Odoo documents (invoices, sales quotes, and sales orders) to have the mailing address on the left instead of the shipping address, primarily for window envelopes. While Odoo doesn't have a straightforward setting for this, you can achieve it through customization.

If you have Odoo Enterprise, the most direct way is using Odoo Studio, a low-code/no-code tool. You can edit the PDF reports directly within Studio, moving the address fields to switch their positions. However, complex layout changes might require some technical knowledge. If you don't have Odoo Studio or need more complex changes, you'll need to create a custom Odoo module, which involves coding in Python and XML. This module would inherit the existing view and modify the position of the address fields. You'd also need to modify the QWeb reports to reflect these changes in the printed/PDF version of the documents. Remember to consider the implications of your changes, ensure data consistency, and test thoroughly.

Hope it helps