Mandrill does not use the updated Mailchimp template?

I am a Python / Vue.js developer who has been asked to access an existing website and make some changes.

One of the changes that I have been asked to make is to update the address that appears at the bottom of the emails that come out on behalf of the website. Emails are sent with Mandrill using Mailchimp.

I updated the email templates in Mailchimp that the website seems to use, but when I tried to create a new user account, they sent me an email that had the previous address at the bottom.

Why did that happen? Do the changes take time to spread? Didn't I update it in the right place?