Avoid falling into costly app traps Apple maintains that controls on its operating system allow parents to restrict this type of purchase. The company made changes in March last year, so there is now an extra password request, reducing the risk of children generating alarming bills. However, unless parents have recently updated their Apple software, they are still vulnerable to a hefty "Smurfberry" bill. For those who wish to ensure they are protected, updating software is very straightforward and should take just an hour or so, said Tom Wiggins, deputy editor of gadget magazine Stuff. The following tips should ensure you can safely hand your phone to your children. Update the software "Updating the software on an iPad or iPhone can be done on the device itself," Mr Wiggins said. "To check if a newer version is available to download and install, parents should go to the 'Settings" menu, scroll down and select 'General," then choose 'Software Update."" Apple recommends always backing up data before updating or restoring. To learn how to do this, visit support.apple.com/kb/HT1766. If you choose to update when you are not connected to your computer, you will need to use Wi‑Fi instead of 3G, as the file size will be too big. Alternatively, if you connect your device to your computer, a pop-up window will say if your software is out of date and you will be prompted to install the latest version. Disable the purchase function Another option is to disable the in-app purchases function on your Apple device. To do this, go to "Settings," select "General," tap "Restrictions" and select "Enable Restrictions." Here you must create a unique four-digit passcode, then scroll down to "Allowed Content" and turn off "In-app Purchases." Bear in mind that unless you adjust the time necessary before a password is required to purchase content, it will automatically allocate a 15-minute time limit. This will mean that if it has been less than a quarter of an hour since you downloaded the app or made an in-app purchase, your children will not be required to type in your password again, potentially racking up a huge bill without inputting any additional details. Use Airplane Mode Even if you aren't flying, this will block all downloads and in-app purchases. To do this on an iPhone or iPad, go to "General," select "Settings" and then turn "Airplane Mode" to the on setting. Gift card option For the parents of teenagers who wish to make purchases on their own device, but who do not have their own bank account, using an iTunes gift card instead of your credit card will help avoid unwanted costs. Get Google savvy It is not only Apple products that can leave parents facing potentially hefty bills. With Google's Android, in-app purchasing is also problem, but, as with the iPhone and iPad, there is protection available. To ensure your Android is safe, always activate the "Screen lock" function, which will force users to enter a pattern, pin or a password on the device each time an item is to be bought. To set this up simply go to "Settings" then "Security" - and then you can choose and set it . Similarly, removing bank details from "Google Checkout" can stop this function from being exploited. To remove your information, go to the "Google Checkout" site and log into your account. On the left of the screen will be a link called "Edit payment methods." Follow that and you will get a list of your accounts. Remove your financial details with the delete button. The Android Market will pull your payment information directly from Google Checkout so no apps can be purchased - by yourself or your children. For future purchases, simply re-enter the details on your account.