I have a IPhone 4 model number A1349 an it won't update past a 7.1.2 it says my software is up to date but I know the latest software is at the least a 8.4. Why is that?
The latest iOS version supported by iPhone 4 is 7.1.2. There is no official way to install iOS 8 or newer on older iDevices.
You can find a compatability list on Wikipedia.
Sorry but iOS 9 isn't supported on iPhone 4.
As you can see at the bottom of this page, the oldest supported iPhone is the iPhone 4s.
iOS 8 isn't even available for iPhone 4. As you can see here.
The last supported OS is iOS 7.
I have tried many times to install/update my iPhone 4 by computer, laptop, etc. All of those tries did not work, because the other updates cannot be supported by the iPhone 4 for example; iPhone 4's screen is too small for the updates , some apps might have more GB which your iPhone 4 might have 32 GB or less which is not enough for the other apps in the update. Also that's why you can't download some apps for your phone.