To protect your TextEdit documents from being changed, you can make them "read-only." This is useful for documents such as "read me" files, license agreements, and any other documents you don't want the reader to be able to edit.

To make changes to a read-only TextEdit document that you own, open the document and choose Format > Allow Editing.

You can also control access to your document by locking it or by setting permissions for it using the Info window in the Finder. See Mac OS Help for more information.