How do I select my Azure CLI subscription?
You can always specify which subscription to work in by using the subscription parameter in your command. That parameter is optional. If you don't specify a subscription, the command uses your current, active subscription. The --output parameter is a global parameter, available for all commands.
How do I enable AZ login?
Sign in interactively
Otherwise, open a browser page at https://aka.ms/devicelogin and enter the authorization code displayed in your terminal. If no web browser is available or the web browser fails to open, use device code flow with az login --use-device-code. Sign in with your account credentials in the browser.
How do I check my current Azure subscription?
In Azure Classic / Service Management, Get-AzureSubscription would give a list of subscriptions in the Tenant with an indicator of which was current. There was also a Get-AzureSubscription -Current flag that would give you just the current subscription.