To update the incoming ringtone for calls to your SwitchLine you will need to do the following:
In SwitchUp tap the "Contacts" tab at the bottom of the screen
Find the contact "SwitchUp Incoming Call" and tap on it
Tap "Edit Contact"
Scroll down to "Ringtone" and tap on it
Select a new ringtone from the list and tap "Done" in the upper right.
Save your changes by tapping "Done" again on the contact
--Do NOT modify this contact's phone number or name, as it will cause the app to stop functioning.