Hi, hduc.yds.
Thank you for visiting Apple Support Communities.
I understand that you are experiencing an issue with Safari for iOS. I would recommend clearing all website data, force closing Safari and restart the phone. One this is done test the results.
To clear your history and cookies from Safari in iOS 8, tap Settings > Safari > Clear History and Website Data. In iOS 7 or earlier, tap Clear History and tap Clear Cookies and Data.
To clear other stored information from Safari, tap Settings > Safari > Advanced > Website Data > Remove All Website Data.
Safari web settings on your iPhone, iPad, or iPod touch
Force an app to close in iOS
-Jason H.