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You can open a new note, text message, or anything that allows typing. You keyboard will pop out from the bottom of your screen. If you don't have any messaging apps, you can open your browser, and tap the address bar at the top to open your keyboard. This button will open a list of all your saved keyboards, and allow you to switch between different keyboard layouts. If you don't see this button in the lower-right or lower-left corner, you can swipe down the notification bar from the top, and tap Choose input method on your quick settings panel. Find the keyboard you want to use on the pop-up list, and tap on its name. This will switch your keyboard to the selected layout.
Open your Android's keyboard. Tap the keyboard icon at the bottom of your screen. Select the keyboard you want to use.