Androidde hem yatay hemde dikey uygulama ...

Merhaba Betül;

 

 <activity android:name=".MainActivity"
            android:screenOrientation="fullSensor"> // bu satırı eklemen yeterli
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
 </activity>