If you have an iPhone, iPad, or iPod touch used by kids in your household, you may find Apple’s default password policy for in-app purchases to be less than ideal. By default, iOS only prompts for a passcode for App Store purchases after 15 minutes have elapsed since the last purchase, and no longer prompts for a passcode at all when installing previously purchased apps or updating apps that are already on your device. Fortunately, this can easily be changed by a quick trip into your device Restrictions, found under the General section in the main iOS Settings app. If you haven’t setup any parental restrictions on this device already, you’ll need to tap the “Enable Restrictions” button at the top and set a four-digit passcode that will be required to access the Restrictions settings in the future. Once you’ve done this, scroll down to the “Require Password” option and tap on it to change the setting from “15 minutes” to “immediately.”
This will not only require a passcode to be entered for every purchase, regardless of how much time has expired since the last one, but will also require a passcode for installing previously purchased apps and updating existing ones—basically for purchasing or downloading any content from the App Store.