If you want to edit your Shopify newsletter popup, first you will need to login to your Shopify account. Next, you will need to go to the Settings section of your Shopify account and then click on the Emails tab. You will then need to scroll down and find the Newsletter popup that you would like to edit. Once you find the Newsletter popup, you will need to click on the Edit button next to it.
You will then be able to modify the content of the Newsletter popup by entering new text or by editing the existing content. After you have finished modifying the content, you will need to click on the Save button in order for the changes to take effect. Finally, you will need to click on the Send Newsletter button in order for the changes to be sent out to all of your subscribers.