You need to split the database:
This creates a frontend and a backend to your database. The frontend
contains all the forms, queries, reports, macros and modules and the backend
contains all the tables. Save the backend of the database on your server
where everyone has access and the frontends on the individual users computers.
This means all your users are using the same data so any change is visible
by all real time.
Access Database Designer
(I have no access to other sites apart from microsoft.com so posting
external links is no use to me)