Configuring default primary address book for editing my contacts about simple-contacts HOT 1 CLOSED

I think there isn't and really you would have to specify a complete ordering of all accounts, not only one primary, to solve this thoroughly. It seems there is some automatic detection which computes a string reprentation of the contact per account and uses the account with the longest representation as primary. This works reasonably fine for me (though not a Signal use, I must admit). If not, you can still click on the account name at the bottom of the contact view instead of the edit button on top.
If that doesn't help you might try to discuss the issue with tibbi, the original author. His changes will also land in this fork eventuall.

from simple-contacts.