One of the smaller changes with iOS 9 is the appearance of the keyboard when using the Shift key. Before, the keys were uppercase in appearance and the highlighted shift key was the only way to know you were typing in uppercase. With the update, the keys are lowercase except when Shift is active: the entire keyboard changes to uppercase. This can make it easier to know which case you're typing in; however, if you prefer the previous set-up, there's a simple Settings change to turn the lowercase keys off.
Open Settings. Select General.
Tap Accessibility.
Scroll down to Keyboard. Turn Show Lowercase Keys off.