If I am teaching multiple sections of the same course, when I submit one section does it automatically update the other sections?

When you edit a syllabus, your changes will only apply to the specific syllabus that you make the changes in, regardless of whether or not you are teaching other sections of the same course. 

If you want to alter specific components so that they are present on all section syllabi, (if enabled) you can utilize course masters.

 Ex: ENGL 101 course master controls ENGL 101-01, ENGL 101-02, and ENGL 101-03.

Jump to What is a Course Master, and How to create a course master.