If your keyboard is "floating" then you should be able to long press the microphone or settings key on the keyboard. You should see a keyboard floating over another keyboard. 4th icon to the right as seen in the picture below.
If the keyboard is not the stock Samsung keyboard, check the keyboard settings.
If you are wanting the Samsung keyboard and the one you are using now is not the stock Samsung keyboard, while in any text box, pull down the notification shade and use the select keyboard selection.