That's a feature, not a bug. Some people use more than one monitor. You should be able to drag a window from your laptop to your TV just like you drag a window from place to place on one screen. Alternatively, you could set the TV to mirror the laptop, but you'd then get the lowest resolution of the two on both. You could also turn off the laptop monitor and have the TV be the only active monitor.
Go to "system settings" via the Dash menu and select "Monitors". You can plat with the settings until you find what you want for your particular viewing needs.