1. Click on the cog icon on the top right-hand corner of MXT, and underneath 'Settings', select ‘SMS Settings'.
2. Under the heading 'SMS and MMS’ you will see the option to set a ‘Default ‘Send From’ Address’. Click on the box below to open the drop-down box of Sender ID options. Select the one that you would like to save as your default Sender ID.
Note: This will be the default sender ID used when you send SMS.
3. Click ‘Update Settings’ to confirm these changes.