Apple isn't happy about its deal with the Federal Trade Commission to pay $32.5m to parents whose children made in-app purchases without permission.

CEO Tim Cook grumbled that the settlement "smacked of double jeopardy" because Apple had already promised to refund affected parents. But the company's willingness to accept responsibility shows it accepts it was at fault.

This isn't just an Apple problem, though. In fact, there are three distinct groups who must shoulder the responsibility of ensuring children don't clean out their parents' bank accounts buying gems, coins, donuts or SmurfBerries.

One group is platform owners: Apple, Google, Microsoft, Amazon and more. The companies that sell devices and run their app stores. The second group is app developers, and the third group is parents.

When I've written about this topic for The Guardian, the comments section has often descended into blaming just one of these groups: platform owners don't care, developers are scammers, or parents are stupid, generally.

The truth? They all have responsibilities around this issue, at a time when more children than ever are using apps, and when in-app purchases have become the dominant way developers make money from the app stores.

Platform owners

Smartphones and tablets are now mainstream in the developed world, and they're sold (tablets particularly) on the basis of their ease of use. Read the f***ing manual? You don't need to: that's the point. Especially when there are step-by-step setup processes the first time you turn the device on.

A good step would be to include parental restrictions in this process: a step that asks 'Will children be using this device?'. If not, it's a single extra tap to move on to the next step. If so, parents could be walked through setting restrictions to ensure that kids can't spend money without their approval.

Educating parents can go beyond this too: Apple has already launched a guide to in-app purchases on its App Store – this could be linked to at the end of that setup process – and it has also made it more obvious on the App Store when an app uses in-app purchases.

This should be standard practice. And the likes of Apple and Google can play a role in other ways too, setting rules for apps designated as being for children (it helps to have a dedicated Kids category on a store) and promoting the best, most ethical ones at the expense of the scammier ones. Talking of which...

App developers and publishers

In-app purchases in children's apps aren't bad and wrong by definition. There are a growing number of kids' apps that use in-app stores to sell digital stories, for example, while others offer a limited free trial with a single purchase to unlock more features.

Many of these apps are great, and take great pains to explain to parents how their in-app purchases work, and trying to hide them away so that younger children in particular won't accidentally stumble on the buying bit. This is good practice.

Other children's apps... aren't so good. They pull every psychological lever they can to persuade children to pay, or to pester their parents to pay. It can be little design touches – last year's Office of Fair Trading report into this subject has a rogues gallery of examples – or gameplay goals geared towards stimulating purchases.

There's a commercial reason not to do this kind of stuff: it alienates parents (once they get to know about it), and word of mouth remains one of the biggest ways people find new children's apps. Or decide to avoid them. There's also a legal reason: regulators are hovering over the market, mulling whether to make examples of less ethical apps.

But really, the best reason to act appropriately is the ethical reason: these are apps and games for children! Whether wilfully naughty or wilfully ignorant – I'm still trying to decide which camp offering £69.99 in-app purchases in a children's game falls into – over-aggressive and/or misleading use of in-app purchases is bad news.

And yet...

Parents

Yeah, parents. We're responsible too, even if a surprise four-figure credit-card bill due to our child running wild in an in-app store will inevitably leave us wanting to blame someone else. That doesn't mean we're stupid or bad parents for getting caught out, but given the media coverage of previous examples, in 2014 we can't really plead ignorance any more.

Step one: if your child is using your device, ensure your in-app purchases restrictions are firmly locked down, and NEVER share your app store password with them. The latter is especially important: an under-reported aspect of this issue is that in many of the cases reported in the media, the child knew their parent's password.

But the wider issue, particularly for older kids, is a traditional parenting skill: talking to our children about their media usage, setting boundaries where appropriate, and perhaps even thinking about finding a way to give them control of their spending – for example a monthly 'digital content' budget as part of their pocket money. iTunes and Google Play vouchers, for example.

A lot of games that end up in the press for children making unapproved purchases aren't actually children's games: Clash of Clans, Candy Crush Saga and Plants vs Zombies being three prominent examples. I'd suggest that the responsibility here lies more on the parent to know what their child is playing, than on the developer to add more child-protection features to their game.

But what about...

Children

Those pesky kids! Shouldn't they shoulder some of the responsibility for their actions? Older ones probably should. Spanked mum or dad's credit card on a chest of gems or two? You're grounded! And you'll be paying it back in instalments. But that's a discipline issue, which brings it back to parents.

Younger children don't necessarily understand what they're doing when buying in-app purchases, especially if they're playing something with some of the dodgy design features laid out in the OFT report. This is where the responsibility comes back to platform owners, developers and parents.

It should be about responsibility rather than blame, though. Also, for every one child in the news for overspending on IAP, there are millions more enjoying creative, educational and/or playful apps. For every dodgy children's developer there are hundreds more behaving ethically.

There's a lot of good happening around children's apps. Sharing the responsibility to tackle IAP bill-shock will help bring the focus back to the positive side.

• 50 best apps for kids from 2013 that parents can trust