Set up Roku account with email A.
Decided to change to using email B but kept email A active for now.
Updated Roku account to use email B. now must use email B to log into Roku account and it shows via Settings/System/Account. (YES)
Subscribed to FUBO. This was thru Roku, email B was in effect on my Roku account at the time.
Unsubscribed from FUBO and received a confirmation email sent to email A. Email came from Roku (email@example.com).