User Configuration > Administrative Templates > Microsoft Office 2016 > Miscellaneous
User
HKCU\software\policies\microsoft\office\16.0\common\internet
This policy setting controls which file links open preference is set as the default for users’ who has not make their selection. For more information about file links handling and open preference in Office, see https://go.microsoft.com/fwlink/?linkid=2277074. User can manually change the default selection anytime. If you enabled this policy setting, file open preference in Word, Excel, PowerPoint, and Outlook will be defaulted to open in Desktop App. If you disable this policy setting, file open preference in Word, Excel, PowerPoint, and Outlook will be defaulted to open in web browser. Note: This policy setting only applies to subscription version of Office.