All settings are stored in files. Those settings files are either stored in the same folder as the SyncBack executable, i.e. where it is installed, or in a user specified folder. Profiles stored in the installation folder can be seen and used by all users with write access to the folder SyncBack is installed into.
You can choose where to put new and imported profiles via burger menu > Global Settings > Settings tab, in V9 (or newer) version (or Preferences > Options menu > 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: