Google announced it has removed the preferred domain setting from the old Google Search Console interface. It is gone - I don't see it anymore and you can no longer set this in Google Search Console.
The feature, I believe, was part of the toolset from launch - I believe. I know they made some changes to it back in 2006 but I believe it launched with the toolset when it first launched. In 2008 they moved it to the settings section and when Google launched the new Google Search Console - Google decided to not move it along and kill it off.
Truth is for years Google has been saying you don't need this setting - you can just use redirects or other methods to communicate the preferred domain to Google. Now Google is saying the same thing "You can find detailed explanations on how to tell us your preference in the Consolidate duplicate URLs help center article. Here are some of the options available to you:"
(1) Use rel="canonical" link tag on HTML pages
(2) Use rel="canonical" HTTP header
(3) Use a sitemap
(4) Use 301 redirects for retired URLs
Google added a super important note: "Note that with the deprecation we will no longer use any existing Search Console preferred domain configuration." That means Google won't be listening to this anymore and you should double check the Google search results to make sure Google is selecting the correct canonical URL for your site going forward.
Forum discussion at Twitter.
