What can cause if I want to download on my App Store and it will go back
i want to upgrade my iPhone 7plus version
Update your iPhone, iPad, or iPod touch
• If you have an iPhone 7, you can update to 15.8.2
Go to Settings > General > Software Update.
This link will show you how to update your iPhone, iPad, or iPod touch using WiFi -
Update your iPhone or iPad - Apple Support
This link will show you how to update using your computer -
Update iOS on iPhone - Apple Support