How to set global dictionary?

Hi. This is probably a pretty basic question.

I want to use the US English dictionary. (It’s color, not colour! :smiley: ) I’ve changed the dictionary on several Scrivenings, but it doesn’t seem to be setting for all of Scrivener. I keep having to change it on different scrivenings.

When I go to change it in a Scrivening that needs it the “spelling and grammar” section is set to “Automatic by language.”

How can I do this in one fell swoop? I do live in Canada, so that may be part of the issue.