Steps
1
Open Prime Video
From the Fire TV home screen.
2
Choose Sign In
Then select I already have a Prime Video membership.
3
Note the code
A 6-character code appears on screen.
4
Go to primevideo.com/mytv
On your phone or computer.
5
Enter code and sign in
Log in with your Amazon credentials.
6
Done
Fire Stick activates automatically.
Switch Accounts
1
Settings
Go to Settings > My Account.
2
Deregister
Choose Amazon Account > Deregister.
3
Register new account
Sign in with a different Amazon account.