New Versions for New Google Script Editor
The new google script editor works in a different way when you update/change the content of your script. If you make a new deployment, then it creates a new script url. We do not want this for our apps, we want the script url to stay the same! In order to ensure this, after editing your script you need to create a new version of the existing deployment. This is how to do it:
1. Save your script
2. On the top right of the editor, click on Deploy, then select Manage Deployments
3. You will get a dialog. At the top right of the dialog is an edit icon (pencil) - click on this.
4. The Version dropdown comes to life. Click on this and select "New version"
5. Enter a Description for your new version if you wish
6. Click on Deploy
7. Test your existing app script url, it should work with the new script content