Q: How can I update to iOS 8.0 on my IPhone?

If this is an iPhone 4S, if you have updated beyond iOS 8, it's not possible to revert to a prior IOS version.

An iPhone 4 can be upgraded to iOS 7.1.2

An iPhone 4S can be upgraded to iOS 9.3.4. There is no way to update to iOS 8.

See the chart below to determine whether you can upgrade your device and what you can upgrade to. If you do not have a Software Update option present on your iDevice, then you are trying to upgrade to iOS 5 or higher. You will have to connect your device to your computer and open iTunes in order to upgrade.

IPhone, iPod Touch, and iPad iOS Compatibility Chart

     Device                                       iOS Verson

iPhone 1                                       iOS 3.1.3

iPhone 3G                                    iOS 4.2.1

iPhone 3GS                                  iOS 6.1.x

iPhone 4                                       iOS 7.1.x

iPhone 4S                                     iOS 9.x.x

iPhone 5                                       iOS 9.x.x

iPhone 5c                                     iOS 9.x.x

iPhone 5s                                     iOS 9.x.x

iPhone 6                                       iOS 9.x.x

iPhone 6 Plus                               iOS 9.x.x

-------------------------------------------------------

iPod Touch 1                               iOS 3.1.3

iPod Touch 2                               iOS 4.2.1

iPod Touch 3                               iOS 5.1.1

iPod Touch 4                               iOS 6.1.x

iPod Touch 5                               iOS 9.x.x

-------------------------------------------------------

iPad 1                                          iOS 5.1.1

iPad 2                                          iOS 9.x.x

iPad 3                                          iOS 9.x.x

iPad 4                                          iOS 9.x.x

iPad Mini & Mini Retina               iOS 9.x.x

iPad Air                                        iOS 9.x.x

=====================================

Select the method most appropriate for your situation.

Upgrading iOS

   1. How to update your iPhone, iPad, or iPod Touch

   2. iPhone Support

   3. iPod Touch Support

   4. iPad Support

     a. Updating Your iOS from iOS 5

          Tap Settings > General > Software Update

     If an update is available there will be an active Update button. If you are current,

     then you will see a gray screen with a message saying your are up to date.

     b. If you are still using iOS 4 — Updating your device to iOS 5 or later.

     c. Resolving update problems

        1. iOS - Unable to update or restore

        2. iOS- Resolving update and restore alert messages

If you’re actually using an iPhone 4S, click here and follow the instructions.

If you’re using an iPhone 4, you can’t.

(144179)

How can I update to iOS 8.0 on my IPhone?

You cannot update to iOS 8.