Hi,

In Odoo 19, the datepicker defaults to MMM d (e.g., Sep 18) because it uses the Luxon library with localized formats, which can be confusing compared to the old MM/dd/yyyy. You can change this by editing the Language → Date Format in settings, but the picker may still show abbreviated months. The most reliable fix is a small JavaScript override in a custom module to force MM/dd/yyyy it everywhere.

Hope it helps