What is the Use Settings From option used for?

This setting allows you to use 1 set of values for your school instead of having to reproduce them across buildings.

Ex: 
High School and Middle School use semesters and want missing assignments to the beginning of the semester while the elementary schools all use trimesters. Set it at the high school and set the middle school to use the high school’s settings. Set 1 elementary school and then the rest of the elementary schools use that school’s settings.

For District users: That setting only applies to options in the Roster Settings tab. Contact Settings are managed at the district only so that there is consistency between the organization.

For Schools on shared servers: That setting will apply to all tabs