Before iOS 9, the onscreen keyboard is fixed with all uppercase characters, irregardless if the shift/caps lock key is on or off. iOS 9 changes the keyboard by displaying lowercase or uppercase characters reflecting the status of the shift/caps lock key status.
It take times to get used to this new “what you see is what you tap” keyboard, and is something you need to adjust to since this will be the default behaviour going forward. But if you’d like to revert back to an all uppercase keyboard again, you can change it using Settings app.
Go to Settings > General > Accessibility > Keyboard. Turn off the switch for “Show Lowercase Keys”. This is not recommended unless you find the lowercase keys too small to read properly.