Modifying a Field to editable

We want to make a field 'Editable = True ’ in sales invoice header.

But in default, the field is non editable.

So, is there anyway to achieve that?

This depends on the version and your license…

From the Development Environment, you can select the table and click DESIGN. Select the field and from the VIEW menu, click properties and then set EDITABLE to TRUE.

If you are on BC 20 and the field is made non editable on table level you can really not change that behavior.
You will have to make a function where the user can insert the new value and update the value in the table in code.

This is a protected table and cannot be modified directly by a customer license. The object calling the modify must be assigned the permission. Unfortunately the permission property is not available to a Page Extension object. This leaves 2 options I can think of. Either create a custom page or a codeunit to handle the modify. To which the permission could be assigned.