How do I change date format everywhere at once?

Like most of the world, I use DMY (let’s not get into my views on MDY), can you please tell me how I can easily change all formats to this, without doing it manually everywhere myself?
Google Sheets, by the way.

Thanks!

I don’t think you’ll be able to do that. That’s usually controlled via formatting, and I don’t think there’s a way to search for formatting in Sheets. Depending on which templates you have installed, each author likely set it up the way they are used to.