Q: My Google Android tablet computer is getting pop-up ads that urge me to download free apps from Google Play (an online app store for devices using the Android operating system). Is there a way to disable these ­pop-ups?

Also, I recently noticed that my tablet has an app I don't recall having downloaded, called Clean Master. Is this app helpful or should I disable it? Where can I learn more about it?

Kathy Finkel, Miami

A: There are several fake pop-up ads that claim to be from the Google Play store. Google says these pop-ups can be eliminated by changing the settings in your tablet's Google Chrome browser.

To prevent pop-up ads from being displayed by Chrome, go to menu, then settings, then site settings. Choose pop-ups, then turn them off.

To clear Chrome of previously viewed browsing data that might contain the pop-ups, go to menu, then settings, then "advanced privacy." Click "clear browsing data." Or, to completely clear all Chrome data, go to settings, then applications. Choose Chrome, then click "clear data."

Clean Master is a legitimate Google Android app that eliminates unneeded software files that were created by apps. It also scans your tablet for malicious software and identifies duplicate photos you've stored. See tinyurl.com/mzkwjkd.

Q: I use Norton Security Suite, Spybot and Malwarebytes software to keep my laptop secure. Are there ­similar apps that I can download for my iPhone 5?

Frank Domurad, White Bear Lake

A: The truth is, there are no comparable programs for the iPhone because it hasn't been plagued by malicious software the way that Windows PCs have been.

But there are apps you can download to help keep your iPhone safer, such as AgileBits ($9.99) which securely stores passwords and financial data, or the free Kaspersky Safe Browser that filters out objectionable websites and those known for malicious activity. For details, see tinyurl.com/qaw84yg. Other iPhone security apps can be found at tinyurl.com/paqjktx.

Q: When I replaced my iPad with a newer version, I transferred the ­settings from the old device to the new one by using a backup of the original iPad that was stored in my online iCloud account. Can I now delete my old iPad backup in order to free up iCloud storage?

Denise Dailey, Orange Park, Fla.

A: Yes, since you've used the backup to update your new iPad, and no longer use the old one, there's no reason to keep the backup file for the original device. For details on how to remove a backup from iCloud, see tinyurl.com/nsx5mtm.

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.