Ability to set a default spell-check language for new documents

Agreed!

This is really annoying, and something that should be really simple to achieve. 

It would also be nice if the list of languages in the User Settings section were the same as the Document Settings!

USER SETTINGS:

DOCUMENT SETTINGS:

Hi ​@Brent Omb, thank you for adding your feedback to this thread and for letting us know just how important this is to you!

Just weighing in that I also find this irritating. In the grand scheme it isn’t a huge deal, but it means wasted brain power for our entire org to verify that it is triggering because I used English instead of US spelling, rather than a valid error. There is no way I will remember to set this every time I open a doc. 
Seems like a pretty basic QoL feature to be absent.

Hi ​@Sam Muller-Speight, I certainly understand how this would impact your use case and workflow! I appreciate you letting us know how important this is to you. Your comment here, and an upvote on the idea, are perfect methods for showing your support for this idea.