Q: I got an email on my iPhone from “Apple iMessages” saying my username and password had been used to log into an iPhone 6. I do have an iPhone 6, but if this is spam, how do they know? I am temporarily ignoring this. What do I do?

A: For years, online criminals have been trying variations of the account-security email for Apple’s iMessages, iTunes and iCloud services to lure recipients into clicking on malicious links or providing Apple ID account information. By including the name of the iPhone model in the message, the sender is hoping to get your attention with specifics. Adding the name of a model still in widespread use broadens the potential audience for the message.

Even if the return address on the message says it is from Apple (or one of its services), you can usually see the account it really came from by tapping the sender’s name in the header. The next screen shows the actual address. If it is clearly not from Apple, forward the message to reportphishing@apple.com.

For more information, search Apple’s support site for its page of other tips for dealing with suspicious email. If you think that you may have been hacked, the site has guidelines for compromised Apple ID accounts, along with instructions for seeing a list of the devices that are using your Apple ID credentials.

Online criminals target Apple ID accounts because they often are linked to credit cards for iTunes or App Store purchases (as are Amazon accounts, Google accounts, bank accounts and so on). Shoring up your personal security with two-step verification and changing your password on a regular basis can help keep your account secure — for your Apple ID and any other e-commerce or social media services you use.

Q. How do I stop Windows 10 from rebooting itself after it automatically installs a software update? I find it does this at night.

A. The current version of the operating system — the Windows 10 Anniversary Update — allows you to block out the time of day you normally use the computer and prevent those automatic restarts that happen after new software is installed. You can set up to 12 “active hours” when Windows is not permitted to restart itself, so if you tend to work on the computer at night, you can set different active hours and let the PC restart itself during the day. (Some test versions of Windows 10 allow 18 active hours, an option that may appear in future system updates.)

To set your active hours, go to the Start Menu and choose Settings, or just press the Windows and I keys on the keyboard. On the Settings screen, select Update & Security and then Windows Update. On the Update Settings area, tap or click “Change active hours.” On the Active Hours screen, set the start and end times in which you want to avoid restarts and click the Save button.

If Windows has installed new updates and has a restart pending that you just want to get out of the way, you can temporarily bypass your active hours settings with a preferred restart time. To do that, go back to the Settings app to Update & Security to Windows Update, and then select Restart Options. On the next screen, set a time for the PC to restart. You can also just get it over with by selecting the Restart Now option on the Windows Update screen.

Stopping Autoplay on Google Chrome

Q. I had Google Chrome for Windows set so Web pages couldn’t start playing videos, but I have noticed over the past few months that the clips play anyway. I didn’t change any of the browser settings, so what happened?

A. You may not have changed the browser’s settings, but the websites you use may have changed the way they handle video. For years, many sites used additional plug-in software like Adobe Flash to show videos — and most Web browsers had settings to stop the plug-in software from automatically playing the clips when the page loaded.

However, many sites have gradually switched from using the video plug-in software and are now using HTML5, which is a language for creating Web pages that embeds the clips in the page. Because the plug-in software you are blocking in the browser settings no longer controls the video, the clip often starts rolling when the page loads.

While most browsers do not include easily reached settings to stop the autoplay videos, you do have some workarounds. For Google Chrome, one option is to go to the online Chrome Web Store and search for the free Disable HTML5 Autoplay extension.

Once you install the extension, it should prevent audio and video clips on Web pages from playing automatically. You can turn the extension off or on from its icon in the Chrome toolbar. A version of the Disable HTML5 Autoplay extension is also available for those using the Opera browser.

Troubles With 911 for Cellphone Users

Q. I saw on the news that a bunch of cell phone users couldn’t connect to the 911 emergency number the other week because of an “outage.” Why is dialling 911 different on a mobile phone than on a landline?

A. When someone dials the national 911 number, a nearby call centre for emergency services (known as a public safety answering point, or PSAP) picks up the call and the operator dispatches medical technicians, the police, firefighters or personnel from another appropriate agency in the area. This month, calls from AT&T Wireless users in at least 14 states would not go through to the emergency network from AT&T’s own cellular airwaves for several hours, possibly because of a malfunction with the software routing the calls to the 911 centers.

Ajit Pai, the chairman of the Federal Communications Commission, issued a statement the day after the disruption to say the agency was looking into the cause. However, AT&T is not the first or only wireless carrier to have problems connecting customers to 911 services. Among the previous cases, an FCC investigation into a Verizon outage and a failure to provide emergency-call service to some subscribers in 2014 resulted in a $3.4 million settlement.

A page devoted to 911 wireless services on the FCC’s website explains the challenge of handling emergency calls from wireless phones instead of wired landlines. The agency notes that because “wireless phones are mobile, they are not associated with one fixed location or address” like landlines. While the mobile phone can provide the location of the nearest cell tower, those coordinates may not be specific enough for a 911 dispatcher to use for directing a responder.

When calling 911 from a wireless phone, be sure to give your exact location and phone number immediately in case you are disconnected.

To help pinpoint calls, almost all carriers use Enhanced 911 services to provide the dispatchers with more precise information, like the geographical coordinates of the mobile phone, but some PSAP centers do not yet have the technology to receive the data. The major national carriers AT&T, Sprint, T-Mobile and Verizon all have information on emergency-calling services on their sites.

— New York Times News Service