All settings are stored in files. Profiles stored in the same folder as SyncBack can be seen and used by all users with write access to the folder SyncBack is run from.
You can choose where to put new and imported profiles via burger menu > Global Settings > Settings tab.
To move your profiles so they are no longer global, review this article:
NOTE: fresh installs store profiles by default in the local user area (for segregation/security: remember that profiles can contain embedded passwords) and profiles are thus user-specific unless that setting is changed: