I believe it is possible for them to change them over one time. you'll have to call in to get it done.
You'll need your customer code to call. Follow the instructions below on how to get it.
https://squareup.com/help/contact
Click “More”
Click "I don't see my issue"
Click "Call Support"
Write down your Customer Code
Call 1 855 700 6000
Depending on your specific account, you might not have phone support available, or you might have limited hours of support. If your account doesn't have phone support, Email is the only way to communicate so that there is proper documentation of the conversations.
if you have a smartphone you can program the phone number with the code into your phone so it will be there next time, store it like this 1 855 700 6000,,xxxxxxxxxxxx. (your code goes where the xs are)(remove the spaces in the phone number). The commas tell the phone to wait 3 seconds each and will automatically enter it for you. Once you set this up one time it is there for all future needs and you won't have to go get your code again.
