If you use multiple Apple devices (Mac, iPad, iPod touch, and the iPhone) or have been given a device by another user, it can be helpful to give each a unique alias for easy handling. This is especially true when integrating payment methods for security and pairing purchases with the correct device.
The name of your device is visible in AirDrop, iCloud backups, when using Find My, and when connecting to a computer for iTunes sync. It may also show up when using personal hotspot or during AirPlay. If you choose to give your device a new name, the change will be immediately updated on all of these services and will be available across all of your devices.
To change the name of your iphone, first tap Settings. On the next screen, you'll see your device's current name at the top of the display. Tap the name to enter editing mode, then delete the existing name and type a new one. The new name will instantly update for iCloud and across all of your connected apps and accessories.
If you'd like to change your iPhone or iPad name from the computer, it's a simple process that's easily done in iTunes. To begin, connect your iOS device to the same computer you normally sync it with and open iTunes. In the sidebar, click the iPhone/iPad icon located in the top left corner of the screen. Click the name in the text field at the top of the window and type in your desired name. Click Sync and your changes will be saved.