The Roku community uses the same password as your Roku user account. You can change your password there at https://my.roku.com/account. If that's where you're trying to change it and it still fails, then you need to send a private message to one of the Roku forum moderators, such as @RokuDanny-R
Dan
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee, just another user.