How to Master your iCloud Backup settings
iCloud settings
Tap Settings > iCloud; if you didn’t enable iCloud during setup, you can here. Decide which services to use. Other accounts added on your other devices, such as Facebook, Twitter, and Gmail, are synced silently too.
Documents & data
Tap iCloud Drive to reveal a switch that turns it on; its app will be added to your Home screen. You can select which apps can store docs and data in iCloud, and whether to use cellular data if Wi-Fi is not available.
Storage & backup
If you turn on iCloud Backup in Settings > iCloud > Backup, your iOS device will no longer sync and back up automatically to iTunes; it’ll back up to iCloud when it’s connected to Wi-Fi and power, and its screen is locked.
Get more storage…
Your account provides 5GB of space for free. If you need more, go to Settings > iCloud > Storage > Change Storage Plan, and tap on the plan you want; 50GB now costs just 99¢ per month, and is enough for many people.
…or optimize first
On the Manage Storage screen, you’ll see your devices that are using iCloud to store their backups, and a summary of your documents and data in iCloud. Tap the name of your device to see details of data it’s backing up.
Delete backups
To save space, remove old data. In the Manage Storage section, tap on an app – depending on the data it stores you’ll be able to delete individual files or entire folders; tap Edit, the red minus icon next to an item, and Delete.
Other devices
For devices other than the one you’re using, you can’t see this level of detail, but you can see when they were last backed up and the size of backups. You can delete backups, but be careful, especially in the case of other devices!
Activate apps
For Apple apps such as Pages, Numbers, and Keynote, tap their name at Settings’ top level and set them to save to iCloud; the app’s docs are then accessible at icloud.com and synced to devices connected to your account.