To do this, from the Roblox app, press the three dots in the bottom right-hand corner, and then scroll down to Settings. Tap that, then Parental Controls. You’ll need to set up a four-digit PIN ...

The Roblox app has more than 30 million players and allows users - who are supposed to be aged between eight and 12 - to "explore virtual worlds" in what looks like a Lego game.