Androidマニフェストでandroid-9固有のテーマを指定したに違いないと思います。例 android:theme="@android:style/Theme.Light"
1) Since Android 4.0 we have Action Bar, so many of the device running Android 4.0 and above will not have Hardware Menu.
2) All your Menu will be in action bar.
3) So, you need to specify different theme to Android v-14 and above, for you app to display Action bar with your menu.otherwise you will not get Action bar so as you Menu.
How To Do It
1) In values/styles.xml
<resources>
<style name="AppBaseTheme" parent="android:Theme.Light"></style>
<style name="AppTheme" parent="AppBaseTheme"> </style>
</resources>
2) In values-v14/styles.xml
<resources>
<style name="AppBaseTheme" parent="android:Theme.Holo.Light.DarkActionBar"></style>
</resources>
3) In AndroidManifest.xml
android:theme="@style/AppTheme"