Account security should always be taken seriously, especially if payment options are connected to the said account.
In this case, Nintendo accounts seem to be the current target of hackers, according to a report from Eurogamer, purchasing various digital items via the paypal option on the eShop. Accounts have been reported across the US, Chile, and Russia but it would be safe to assume that there could be more.
Nintendo is aware of the reports and have thus encouraged users to turn on 2 step verification on their accounts. A detailed list of steps can be accessed from THIS LINK, prompting you to download the Google Authenticator App for iOS or Android as well to complete the process.
You can never be too safe about any of your personal accounts, so take this time to secure them by adding that extra layer of protection if and when available. You wouldn’t want to lose your hard earned funds that you were supposed to buy that next big game with, do you?