Numbers sheet template?

I was able to create a "new document" template that is used every time I create a new document, but when I create a new sheet, it goes back to the format I don't want to use which is the white sheet, the old font, etc. Is there a way to customize the default sheet template? Duplicating a sheet is not always a good option to "fix" this, because sometimes I'm already working on a sheet and I have lots of tables and all that, so I would need to delete all that content.

Here's my template:

Here's the new sheet template that I would like to customize: