How to Update Your Recipient's Address to Keep Sending Letters
Open the Sandboxx app
Click on the "Letters" tab
Select your recipient: Once you select your recipient, you'll see a screen with their address details IF you're connected to them
Simply edit their address details once you see them (NOTE: You'll only see address details if you're connected to the user, or you created them as a "new" user previously)
This is not different on Android or iOS?
Correct, it is not.
Basically, if you can see the address of the recipient when you're composing the letter, you can edit their address.