Azure subscription in Azure Resource manager
If you used to use Azure in classic mode you might get confused about powershell commands in azure resource manager in order to be select your azure subscription follow these commands
PS C:\> Get-AzureRmSubscription –SubscriptionName "your subscription" | Select-AzureRmSubscription
normally remember most of classic model commands will follow with rm and end of the verbs.
read more about it
https://azure.microsoft.com/en-us/documentation/articles/resource-manager-deployment-model/