Iphone 6s ios 9.3.1 keyboard

Hi, In short, you used to be able to press and hold many characters on the iphone keyboard and it would display alternatives, a good example is the £ key, which on my 5s on IOS 9.1 you press it for a longer time and it displays lots of currency signs, such as $ and € and if you do the same on the "E" key you get options for the same letter but with an accent so you can for example type Rémi instead of being stuck writing to Remi. However I have just upgraded to the 6s on IOS 9.3.1 and when you press and hold any key all the keys on the display go blank.

I have rebooted a few times and also removed and replaced the keyboards, anyone got any ideas.

Many thanks