How can i block a interactive forms after i wrote and saved

There are a couple of ways to prevent others from editing the form form fields once you fill them in and most will also prevent you from modifying them.

First there are digital signatures and you can lock the fields when you apply your digital signature. You will have to remove the digital signature before you can edit the fields. Note that the digital signature can alert you if there have been any changes to the signed PDF.

You can flatten the PDF form and make the form fields part of the content of the PDF. This will destroy the form fields ability to be edited or extracted.

You can make the form fields read only and then when you want to edit the form run a script to change the read only property of the fields to false. Of course this may make calculated fields read write which you might not want..

One could also add an advanced script to verify the login ID of the user and then unlock the locked fields when the form is opened by someone using your login ID.