Your Fire TV should update your device automatically. If you want to make sure, go to Settings, then Appstore. You should see On under Automatic updates.
On Fire TV go to Settings
To make sure a particular application is updated
Additional help can be found on Amazon’s support site.
Roku
Your Roku device should update your software and channels automatically. However you want to check manually, follow these instructions.
a. Select Settings
b. Select System
c. Select System Update
d. Select Check Now
2. To make sure a particular application is updated
a. Navigate to the app you wish to update
b. Press *
c. Then click Check for Updates
Additional help on this topic can be found at Roku’s support site.