That's why a factory reset is crucial before you sell, recycle, or donate your Android phone or tablet. It can also be a last-ditch attempt at troubleshooting persistent issues with your device.

Setting up a new phone from scratch is a tedious process, especially when you have to download and sign in to many apps, set up the phone’s settings, and arrange everything the way you like it.

Taking the basic steps—deleting data from or reformatting a computer hard drive, or doing a factory reset on a smart phone or tablet—might be enough to discourage identity thieves. But this ...