Default values for documents like Currency, Fiscal Year, etc, can be set from Global Defaults.
The values set here will impact all users and the default values for various fields will be set for them.
To access Global Defaults, go to:
Home > Settings > Global Defaults
Or search from the search bar.
Whenever a new document is created, these values will be set as default.
The Default Distance Unit is used to calculate the total distance in Delivery Trips.