Can't backup iPhone 4s though iCloud.

Hello!

I currently trying to backup my iPhone through iCloud but it takes forever. It keeps showing "estimate remaining time" instead of backing it up. I tried backing up the phone through iTunes and it successfully backed up. But, when I tried backing up through iCloud, it doesn't backup. There's no problem on iCloud storage and internet connection. I even tried to reset my phone and it still not backing up.

My iPhone used to backup automatically whenever I connected to Wi-Fi/internet but it stops working when I changed my iCloud ID. I can't back up either automatically or manually now.

Appreciate if someone could help!!!!!!