Set a contact's preferred line when you have two SIM cards. This will make the preferred line the default whenever you interact with that contact.
1.
From the Settings app, tap Network and Internet.
2.
Tap SIM cards.
3.
Select Alternate contacts.
4.
Select the contact you would like to move.
5.
Select the SIM you would like to move the contact to.
6.
Select the contact.
The labels you've chosen may differ from this tutorial, but the same steps should still apply.
7.
You've completed the steps!
