Hey, age is not a problem, don't worry! Just ask away and we'll try to help
First, the method you're trying. That would only change the default storage for downloads initiated from the Internet app (that's your browser, and those downloads are like files, pictures, songs, etc.). Apps, even if you initiate the link from the browser, are handled by the Play Store, and that won't save to SD card automatically. Like I mentioned, as part of the system security, all apps will always be downloaded/installed directly to internal memory.
Now, depending on the dev, they can set some options to be moved to SD card (for instance, your browser let you download files to SD card; other examples of basic features include the camera allowing you to save to SD card, or Spotify offline files, Netflix offline movies, etc.).. If you want to move an app to the SD card, it gets tricky, so bear with me.
Like I mentioned before, you won't be able to move ALL of the app. The main file will always reside in internal memory because of how the OS is designed. IF the dev allowed some parts of the app to be moved to SD card, then you would have to do that from the Application Manager. To get to that, you have either the option to go to your tablet's Settings and finding the Apps option or when on your app list, long press on the app you want to move and select the Info option. In the app's info screen, you should see a STORAGE option. In there, IF the dev allowed anything to be moved, you'd find the Move to SD card option.
Bear in mind that when an app updates, even if you moved it to SD card, it will move back to internal memory for updating and you'll have to manually move it back to the card if you so wish.
Also, since the SD card can be easily damaged/removed, any app that was moved will cease to work if you remove the card and can lead to issues with it when you re-insert it if it was done with the tablet on.