Hello! There are a few ways to upgrade the software version on your iPhone 6 Plus:
1. Over the Air (OTA) Update - This is the easiest and most common way to update your iPhone's software. To do this, go to Settings > General > Software Update. Your iPhone will automatically check for available updates and you can download and install the latest version of iOS from there.
2. Update via iTunes - If you're unable to update your iPhone over the air, you can also update it via iTunes on your computer. Connect your iPhone to your computer and open iTunes. Click on the device icon and then click on "Check for Update." If an update is available, click "Download and Update."
3. Using IPSW File - If you're having issues with the above methods, you can try downloading the iOS software update file (IPSW file) from the internet and installing it on your iPhone via iTunes. This method is a bit more technical and requires more steps, so it's recommended for advanced users.
It's important to note that before updating your iPhone's software, you should back up your data to prevent any potential loss of data during the update process. Also, make sure your iPhone has enough battery life or connect it to a power source before updating.
