Mark needs to prove where he was to someone. Leo says that you can see where you've been by going to google.com/dashboard. Click on maps, then more, then timeline. If it's enabled in the application settings, you will see a history of where your phone has checked in within the network. It should go as far back as 18 months at least. If that isn't good enough, you could contact your carrier as they will have that information available. But that information is only available to law enforcement as they can get access to that information without a warrant. So using Google is your best bet.
Mike just upgraded to iOS 11.1 and he's wondering if turning off Background App Refresh and Location Services will save battery life. Does it make a difference? Leo says that he would do that for privacy issues rather than battery life. It's a good idea to change it to use his location only when the app is working. Apple would let him decide both by app. Leo does recommend leaving it on for his maps app, though. Apple does a very good job of managing battery life, and in most cases, turning off all those services is a finesse he doesn't need to really hassle with.