How can I change non-working days for all sheets in my account

It seems pointless to set non-working days as a default within the Admin Console and/or sheet since changes don't seem to apply to any sheets unless they are brand new. None of my existing project sheets reflect changes - templates seem to inherit whatever was in the settings at the time the template was created.

Please tell me there is a way for me to propagate non-working days & holidays across sheets. Any advice / direction would be greatly appreciated!!🙏