Workgroup Manager question


Hi All, new to the world of MAC OS. Trying to learn Work group manager to manage 48 Macbooks.
In work group manager I have 3 Computer groups; All computers/Student Computers/Teacher Computers. All the laptops are listed in All and Student, with teacher being empty for now.
My questions:
1) Should I be making changes in just the ALL Computers group? And if I made changes in BOTH ALL and Student... which overrides which?

2) If I made changes in both (not sure WHY I did this) how Can i get the ALL computers to be the 'ruler' of my settings?

Thanks in advance... Still learning- lots of stuff on this forum too!