Google recently did a make-over of the Contacts page to use the newer ‘material design’ look, as I recently described in this post. One feature that was lost in this update (and was sadly missed by many users) is the ability to sort contacts either by first name OR last name.
Google have now corrected this. Look for the A-Z icon at the top right, and click it to reveal the two options:
Note that the chosen search option also determines how the names are displayed in the contact list. If you sort by last name, the names will be displayed in Lastname, Firstname format; sort by first name, and they’ll be shown as Firstname Lastname.
[Note also that the sort order in the Frequently Contacted section will always be by contact frequency, irrespective of your sort order choice. All that will change in this section will be the name display format.]