I have an 2010 iMac running High Sierra. I have iTunes version 126.96.36.199 and iOS version 12.3.1. I want to backup my iPhone to my computer using iTunes.
In the past I could connect my iPhone to my computer and when I started iTunes the iPhone icon would appear on the left side on the iTunes screen. I would select the iPhone and then back it up to either my computer or to iCloud.
Now, however, the iPhone does not appear in iTunes. How do I backup my iPhone to my computer?