Samsung Galaxy S II Online User's Manual page 82

Device Administration
Use Device administration settings to control device
administrators and installation of apps from unknown
sources.
Select one or more device administration options to
control your device for security purposes (for example,
if your phone is lost or stolen). These applications
enforce remote or local device security policies.
Some features a device administrator might control are:
Setting the number of failed password attempts
before the device is restored to factory settings.
Automatically locking the device.
Restoring factory settings.
Note:
If you have multiple device administrators enabled, the
strictest policy is enforced.
67 2C. Settings
1. Press and tap
2. Configure options:
Device administrators
administrators. Select a device administrator and
follow the prompts. Available device
administrators depend on the applications
installed, or accounts set up on the phone.
: allows you to choose whether
Unknown sources
to allow installation of apps from sources other
than the Play Store.
WARNING:
Enabling this option makes your phone and
personal data more vulnerable to applications
from unknown sources.
.
> Settings > Security
: allows you to select device