For individual sites go to the settings page and update the SITE URL and Address.
For multisites / network installs I must enter enter it in the Network Settings Page or if it’s not there enter it manually in the wp_config.php
page.
I’m also making sure that any one that enters http instead of https is redirected to the https version of the site. I can do this on the domain name / SSL settings page or in the .htaccess file in the root of the blog install.