Here's how you could update your signature so you could change your default return address.
Open your DealMachine account.
Select an existing template and click Edit.
Click the Signature Option on the top right corner.
Select a Signature you want to edit and click the 3 dots right next to it.
Scroll down until you see the option to change your return address.
Hope this helps. If you have questions, please reach out to our Customer Support Team through the Help option in the app or the website.
Live Support is available from 8 AM - 10 PM EST on weekdays and 10 AM - 10 PM EST on weekends.