Clean up your WordPress website’s HTTPS insecure content and mixed content warnings. Installing the SSL Insecure Content Fixer plugin will solve most insecure content warnings with little or no effort.
When you install SSL Insecure Content Fixer, its default settings are activated and it will automatically perform some basic fixes on your website using the Simple fix level. You can select more comprehensive fix levels as needed by your website.
WordPress Multisite gets a network settings page. This can be used to set default settings for all sites within a network, so that network administrators only need to specify settings on sites that have requirements differing from the network defaults.
See the SSL Insecure Content Fixer website for more details.