Cloze will automatically sort the last phone number you have used for a phone conversation to the top. If you would like to set a preferred phone number (work, personal or overall) instead for a contact, you can do this in the edit section of the contact record. 

Cloze will then always sort the preferred phone number to the top for your contact.

 

 

Select the Contact Info tab:

 

Select the preferred phone number:

 

Once a preferred phone number is selected for work and/or personal, you can select an overall preferred phone number: