<activity android:name=".SilverballSmashActivity"
  android:screenOrientation="portrait" 
  android:configChanges="orientation|keyboardHidden"         
  android:theme="@android:style/Theme.Translucent.NoTitleBar" 
  android:label="@string/app_name">
  <intent-filter>
    <action android:name="android.intent.action.MAIN" />
    <category android:name="android.intent.category.LAUNCHER" />
  </intent-filter>
</activity>
 
<activity android:name=".AppSettings"
  android:screenOrientation="portrait" 
  android:configChanges="orientation|keyboardHidden"         
/>
 
<activity android:name=".hiscore.HiscoresList"
  android:screenOrientation="portrait" 
  android:configChanges="orientation|keyboardHidden"         
/>
 
And then in your Activity:
 
@Override 
public void onConfigurationChanged(Configuration newCfg) { 
  //ignore orientation change 
  super.onConfigurationChanged(newCfg); 
}