User Configuration > Administrative Templates > Microsoft Project 2016 > Project Options > Interface > Project Guide settings for 'Project1'
User
HKCU\software\policies\microsoft\office\16.0\ms project\options\interface
Specifies whether the side pane displays the Project Guide content that comes with Project or custom content that your organization has developed. If you enable this setting, content for the Project Guide is loaded from the specified location. If you disable or do not configure this setting, the user's default setting is used.