The latest version of Analytics integration plugin for WordPress uses the new gtag.js tracking code as recommended by Google, but only for new installations. If you upgraded the plugin from an earlier version, your tracking code will remain unchanged. This is for the sake of compatibility, as we don’t want to break your eventual customisations (your own custom dimensions, events, goals).
If you upgrade the plugin, it will require you to explicitly choose which tracking code you want to use by going at the bottom of Settings > General and resubmit the form by either leaving the box Use old analytics.js checked and continue using the old code or uncheck the box and use the new gtag.js
If this plugin is everything you have regarding google analytics and there is no custom analytics code for tracking special events in your theme, child-theme or any other plugins, then it’s safe and recommended to switch to new code.
If you are a new user, thanks for installing the plugin and you will decide which code to use when you will enter the tracking code. The new code is definitely cooler.
From this version on, the plugin is also localization ready.