Set My Region / Language Preference (Language, Date/Time Formats)

Set it and fuggedaboutit (i.e. you only need to set it once).

Volunteer or Voluntario? dd/mm/yy or mm/dd/yy? 3:45pm or 15:45?

One setting takes care of it all. Yours is probably already where it ought to be but you can change it if is not.

Selecting the region / language setting

This will enable you to change the language that is used. Selecting the desired region value from the list will also adjust the formatting of dates and times you will see.