Q: Because there are features of Windows 7 that will be eliminated by upgrading a PC to Windows 10 (such as DVD software and some games), some of us may decide we don't like it. Will it be possible to easily revert to ­Windows 7 if I change my mind about Windows 10?

Tom Bartlett, Moultonborough, N.H.

A: Microsoft has made it surprisingly easy to return your PC to Windows 7 or Windows 8.1, as long as you do it within one month of upgrading to Windows 10. A file stored on the C drive called "Windows.old" contains the files needed to return to your previous operating system. After a month, that file is automatically deleted to save hard disk space.

To uninstall Windows 10 within the first month, go to the Start menu and choose "settings." From the resulting menu, choose "update and security," then click "recovery." You'll be given the option to "go back" to Windows 7 or Windows 8.1, depending on what you had previously. Click "get started." Your previous version of Windows will then be restored, and Windows 10 will be gone. For details, see tinyurl.com/pta5nw2.

If you wait longer than a month to change your mind, you'll have to return to your earlier operating system the hard way, by using an original install disk or by downloading a copy of your previous operating system from Microsoft. Either method wipes out any data or programs you've accumulated since you bought the ­computer.

To download your old operating system, you'll need the PC's "product key" to prove to Microsoft that you're entitled to do so. The product key will be on a "certificate of authenticity" sticker on the outside of the PC, stored in a computer file or embedded in a PC computer chip. For help finding it, see tinyurl.com/nch3av6. For details on downloading old versions of Windows, see tinyurl.com/knfxe3b for Windows 7 or tinyurl.com/bkpy97u for Windows 8.1

Q: I use the e-mail system of my ­Internet service provider, Frontier.com, but I'm having trouble downloading e-mail attachments. I get a message asking me to retry the download, but that never works. I already tried doing a system restore on my Windows 7 PC, but that didn't help.

Jim Morton, Minnetonka

A: The problem may be either your Windows settings or your Frontier e-mail system.

Windows 7, 8 or 8.1 may be set to restrict downloads for security. For some potential fixes, such as changing Windows settings, clearing the browser's cache (where previously downloaded material is stored) and storing downloads under new file names, see tinyurl.com/mzjbjjq.

If those techniques don't work, set up a Google Gmail account at gmail.com. Then forward one of the troublesome e-mails to the Gmail account. If you can download the attachment using Gmail, you'll know that the fault lies with the Frontier e-mail system.

E-mail tech questions to steve.j.alexander@gmail.com or write to Tech Q&A, 650 3rd Av. S., Suite 1300, ­Minneapolis, MN 55488. Include name, city and telephone number.