This Message is From Adobe Customer Care
Creative Cloud login is meant to linger, so the user doesn’t have to continually log in. Logging out of the OS user account does not log you out of the Creative Cloud. However, CC login is local to the user account. So, if user logs into a different user account they should not see the other use CC login.
Is this a shared device such as in a lab or classroom? If so, are you working with Shared Device Licensing? If this is the case, the login does linger, but it is limited to 90 minutes before it verifies the user is still operating the computer. This is to help prevent issues of overlap between users but it is not a perfect system as 90 minutes is too long for some and not long enough for others.
To full prevent overlap, the users should log themselves out after they are done with their session. Potentially, you could script something into the OS logout that will remove the “cookie” files which store the CC credentials. This document talks about how we store user credentials: https://helpx.adobe.com/download-install/kb/adobe-license-issues-keychain-credential-mgr.html