Q: The battery go down very quickly

Hey there Nour elkady,

Welcome to Apple Support Communities.

From what I gather, there's an issue with battery life not lasting as long as expected with your iPhone 6. Try taking a look at the article linked below which will walk you through the process of checking battery usage by apps and adjusting settings to improve your device's battery life.

About the battery usage on your iPhone, iPad, and iPod touch - Apple Support

Also, this article provides a lot of great additional information that can help you increase your iPhone's battery life:

Batteries - Maximizing Performance - Apple

Take care.