How to properly download and install iOS 9 on iPhone, iPad, and iPod?

Question

I want to upgrade my mother's iPhone 4s and my iPhone 6 to the latest iOS 9 system, but I am afraid that I will lost my data from iPhone after iOS upgrade. What do I need to be ready for the upgrade and how can I properly download and install iOS 9 on my iPhone and iPad/iPod without losing data?

Answer 1

You will not lose the data after the upgrade to the iOS 9. The update procedure is configured to keep the data, no matter what. However, you can create a backup by connecting the device to PC and use iTunes. Manually connect each device, then from iTunes, go to File > Devices > Back up. This procedure will create a backup to restore later, in case something goes wrong.

Secondly, to update the iOS, the devices can use the wireless way or the iTunes way:

1. Wireless Wifi: Connect the devices to WiFi and then go to Settings > General > Software Update. Make sure you have enough battery (85%+) and then download and update the device.

2. Connect to iTunes and click the Check for Update button on the main interface. Download and apply the update.

Back up info page: https://support.apple.com/en-us/HT203977
Update info page: https://support.apple.com/en-us/HT204204