network Security

Hi all,

Am new to the IT field,Accounting & Inventory were my speciality. Am a Backup IT assistant My IT sup is off on holidays,so am just studying the system.
I have notice that on some drives when I check the properties and security everyone has access while on others folders within the drives different user access for example this is how my network is layed out
I:drive contains users files the security on this seems to be ok as users has access to the files they or to.
H:drive contain users home folders,this seems ok to.
L:drive contains data and everyone has access
G:drive contains apps and everyone has access
s:drive contains data and everyone has access.

should the administrator alone has rights to add,modify,delete,& read information on the (L,G,S)drives.If so What should I do.please advice