MS Access Workgroup question

[BlueJay924]

I was finally able to create and join a workgroup. However, my concern is that when i join a new workgroup, the database that i thought i secured is no longer secure. Whatever users/passwords i had for the database no longer applies when i join a different workgroup. Is there a way to secure a particular database and not be asked for a username and password for a different database? If not, it seems that only one work group controls all the databases.