I noticed there are some differences in how the app name can turn up in Lollipop devices. Before Lollipop, you can have different app names with this:
<application
    android:label="@string/app_name"> // appears in manage app info
    <activity
        android:name=".MainActivity"
        android:label="@string/action_bar_title"> // appears in actionbar title 
        <intent-filter android:label="@string/name_in_icon_launcher"> // appears in icon launcher
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
...
In Lollipop, it will be like this:
<application
    android:label="@string/name_in_manage_app_info">
    <activity
        android:name=".MainActivity"
        android:label="@string/name_in_actionbar_and_icon_launcher">
        <intent-filter android:label="@string/this_is_useless">
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
In Lollipop, android:label in intent-filter is basically useless, while actionbar title and icon launcher is identical. So, if you want a different title in actionbar, you have no choice but to set dynamically
getSupportActionBar().setTitle(R.string.app_name);