Q: We have an HP Officejet 4500 printer, and are able to print wirelessly to it from my HP PC and my wife's Mac. But we can't print wirelessly from our two new iPhone XS models because neither of them recognizes the HP printer. Is the printer installed incorrectly, or is it just too old to work with the iPhones?
Rudi Gutmann, Minneapolis
A: Your printer, which was introduced in 2010, can't use the newer wireless printing technology built into the iPhones. But you may be able to wirelessly print using other for-pay iPhone apps.
The HP Officejet 4500 was designed to accept wireless printing requests from PCs and Macs that are on the same Wi-Fi network. But it can't accept printing requests from the iPhone's AirPrint wireless printing software, which works either over a home Wi-Fi network or directly between an iPhone and a printer.
Normally, you would turn to an alternative wireless printing method, such as HP's ePrint service (it e-mails documents to the printer) or Google Cloud Print (it sends cloud-stored documents to the printer.) But the Officejet 4500 is just old enough that it isn't compatible with either of them.
That leaves you with third-party iPhone apps that are designed to wirelessly connect to older printers like yours. They include Printer Pro ($7) and PrintCentral Pro ($6), which are available in the Apple App Store.
If you would rather buy another printer, Apple maintains a list of AirPrint-compatible printers from all manufacturers (see tinyurl.com/ou6jobs) .
Q: I'm unable to hear any sound when I try to view video clips or listen to music on my Windows 7 PC from HP. When I hover my mouse pointer over the speaker symbol in the PC's task bar, I get the message "No audio output device is installed." What should I do?
Keith Knefelkamp, Victoria, Minn.
A: HP said the lack of sound is probably caused by the PC's audio software driver. Software drivers connect programs to the PC's components, such as the speakers.
For directions on how to fix the problem in Windows 7 (including how to reinstall or replace the audio software driver), go to HP's help page (see tinyurl.com/y47r4xt2). Click "enable the audio device in Windows 7."
Some Windows 10 users may be having a similar problem for a different reason: An automatic Windows 10 update accidentally installed the wrong audio software driver on some PCs.
Microsoft has provided an automatic fix for PC owners with a 64-bit version of Windows 10. To get it, download Microsoft software patch number KB4468550 (see tinyurl.com/y6rkyatc). It corrects the error in Windows 10 update 1809 that was introduced last November.
If you have the 32-bit version of Windows 10, or if you prefer to correct the problem yourself, you can manually install the correct audio software driver (see tinyurl.com/y3u25qsb).
If you don't know whether you have the 32-bit or 64-bit version of Windows 10 (the main difference is in the way they handle PC memory), open the Control Panel. In the "view by category" drop-down menu, select "large icons." In the resulting menu, click "system" and check the "system type."
E-mail tech questions to email@example.com. Include name, city and telephone number.