When you double-click a document, macOS uses the document’s file extension to figure out which app should open the file. So, by default, a PDF file called laser-squid.pdf opens in Preview because the Finder knows that everything with a .pdf extension should open in Preview. But what if you would prefer to open .pdf files in Adobe Reader, or you want comma-separated value (.csv) text files to open in Numbers? To change any mapping, select a file of the type in question and choose File > Get Info to open the Info window. In the Open With section, click the pop-up menu to choose the desired app and then click the Change All button.




When you register your fingerprints with Touch ID or train Face ID to recognize your face, it’s reasonable to worry about that information being stored where attackers—or some government agency—could access it and use it for nefarious purposes. Apple was concerned about that too, so these systems don’t store images of your fingerprints or face, but instead mathematical signatures based on them. Those signatures are kept only locally, in the Secure Enclave security coprocessor that’s part of the CPU of the iPhone and iPad—and on Touch ID-equipped laptops—in such a way that the images can’t be reverse engineered from the signatures.
People with medical conditions can be concerned about health information impacting health insurance bills or a potential employer’s hiring decision. To assuage that worry, Apple lets you choose what information ends up in Health app, and once it’s there, encrypts it whenever your iPhone is locked. Plus, any Health data that’s backed up to iCloud is encrypted both in transit and when it’s stored on Apple’s servers.
A linchpin in Apple’s approach to privacy is its control over the App Store. Since developers must submit apps to Apple for approval, Apple can enforce stringent guidelines that specify how apps can ask for access to your data (location, photos, contacts, etc.). This isn’t a blanket protection—for instance, if you allow a social media app <cough>Facebook<cough> to access your contacts and location, the company behind that app will get lots of data on your whereabouts and can even cross-reference that with the locations of everyone in your contact list who also uses the service.