Simply head over to the Popups dashboard:

Find the popup that you want to edit, and look for the ‘Actions’ button on the right side. Click on it.

A drop down will open up which will have the link: “Edit Popup”.

Clicking on that will take you to the Popup composer and there you can make changes. Make sure to SAVE your changes before leaving that page.

Note: Editing a popup and saving it will automatically start reflecting wherever you have pasted the embed code for that popup. You won’t need to paste the embed code again and again.