Good day, and welcome to the Community, Matteo_S. I'd like to offer my help regarding your inquiry about adding shipping details to your sales transactions.

If you're still in the old layout, start by making sure the Shipping feature was not accidentally turned off in your company settings. If deactivated, the shipping fields will no longer show up when creating sales transactions.

Let me share this article on how to verify if it's turned on or off: Add A Customer’s Shipping Address To Invoices In QuickBooks Online.

If you can't still see it, there's a chance this is caused by a browser-related technical issue. You can clear your browser's cache and cookies or try a different web browser to isolate the issue. Chrome, Firefox, Microsoft Edge, and Safari are all compatible with QBO.  

If you've already switched to the new layout, I want to inform you that some fields are not yet supported. This is why they are not showing up when you create estimates, even if they are part of the template. 

Our product team is currently working on bringing over legacy features, such as customized shipping fields.

For now, a workaround is to use Custom Fields to add your shipping details to estimates and invoices if you're using QBO Advanced. Here's a guide on using this feature: Create And Edit Custom Fields In QuickBooks Online Advanced.

Please feel free to reach back out to the QuickBooks Community if you need any other assistance customizing estimates, or managing sales transactions in your account, Matteo_S. There are always fellow community members here to help.