On your computer, open Chrome. In the top-right, click More. In the 'Default browser' section, click Make Google Chrome the default browser. If you don't see the button, Google. Read more: chrome default browser. When you set google chrome as your default browse.
Have you downloaded the Chrome Administrative Templates? https://support.google.com/chrome/a/answer/187202?hl=en
Specifically this setting: DefaultBrowserSettingEnabled
Chrome Default Browser Mac
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Configures the default browser checks in Google Chrome and prevents users from changing them.
Chrome Default Browser Cmd
If you enable this setting, Google Chrome will always check on startup whether it is the default browser and automatically register itself if possible.
If this setting is disabled, Google Chrome will never check if it is the default browser and will disable user controls for setting this option.
If this setting is not set, Google Chrome will allow the user to control whether it is the default browser and whether user notifications should be shown when it isn't.'