I usually hand over my Samsung Note 3 to my kids to watch Netflix , videos and play games etc. I recently notice that my status bar will not take off, I looked at every settings option, and I can't find the option to turn it off. I would appreciate if someone can help me thank you.
If you are on Android Lollipop then as Izzy suggested, you can turn on the Screen Pinning to stay in a particular app and hide the status bar.
If not on Lollipop then third party launchers such as Apex and Nova allow you to do this only in the home screen and app drawer screen.
As in the feature section you can see that you can hide the status bar,
Hide elements as you want (persistent search bar, status bar, or even the dock)
But this only hides the status bar in Home screen and the status bar becomes active once you open a specific app. Instead the developer of the app should have implemented the immersive model to hide the status and action bar.
But as mentioned in your question most games will hide the status bar and videos played with fullscreen does hides the status bar.
Use Power Toggles and in the toggle actions use the Immersive mode and start any app you want. The app will start with the status bar and the action bar(Back, Home and Recent buttons) hidden and you can switch back to normal mode by clicking the toggling Immersive mode or to quicky display the status bar swipe from the top of the screen twice to display any notifications.