Policy
Show custom templates tab by default in Excel on the Office Start screen and in File | New
This policy setting controls whether custom templates (when they exist) show as the default tab in Excel on the Office Start screen and in File | New. If you enable this policy setting, users will the see custom templates tab as the default tab in Excel on the Office Start screen and in File | New when templates exist (this can include Custom XML programmed templates, templates in the Workgroup templates path, templates in the Personal templates path, or SharePoint templates). If you disable or do not configure this policy setting, users will see the Featured templates tab as the default tab in Excel on the Office Start screen and in File | New, unless all Office-provided templates have been disabled.
939dfed3be3b L_DefaultCustomTab Registry
Copy registry mappings
HKCU\software\policies\microsoft\office\16.0\excel\options\officestartdefaulttab (enabled) = 1
HKCU\software\policies\microsoft\office\16.0\excel\options\officestartdefaulttab (disabled) = 0Policy notes
This policy setting controls whether custom templates (when they exist) show as the default tab in Excel on the Office Start screen and in File | New. If you enable this policy setting, users will the see custom templates tab as the default tab in Excel on the Office Start screen and in File | New when templates exist (this can include Custom XML programmed templates, templates in the Workgroup templates path, templates in the Personal templates path, or SharePoint templates). If you disable or do not configure this policy setting, users will see the Featured templates tab as the default tab in Excel on the Office Start screen and in File | New, unless all Office-provided templates have been disabled.