I am from Europe. About the dates, for me it depends.
In personal things, I generally use the American date format because I got used to it. And when going through a list of things month first is often nicer to look at.

When giving something to someone else, I use date compatible with RFC3339 and ISO8601 standards (YYYY-MM-DD).
Quick comparison between the two: ijmacd.github.io/rfc3339-iso8601/

But people have questioned me about both, since DD. MM. [YY]YY is basically the only format used in my country, but I don’t like it.