Default number format (thousands separator, decimal marker) and date format (country specific)

[GISMountains]

Hello

How can we change the default number format in "ArcGIS Online" and "Portal for ArcGIS"?
thousands separators --> space or ' (high comma)
decimal marker --> . (point)

And how we can change the default date format to country specific format?

We set the "culture" and "region" in the "ArcGIS Portal"-Settings and the region in AGOL without any changes?!?

Cheers