The settings in the MediaShout Remote preferences allow you to control access by devices attempting to control or view the presentation. This can be important for a number of reasons. While you obviously don't want anyone who downloaded the app to be able to control your presentation. Because the server in MediaShout communicates with each connected Remote app separately, you may also want to limit access to the viewer option as well to prevent poor performance. Nearly any combination of access control is possible by adjusting the Presenter check-box and the password entries.
These settings are accessed in v4.5 by going to Tools > Settings... > Remotes. In the Mac version they're under MediaShout > Preferences... > Remote.