Hi @BW18 check the eail you used when signing up for anything in the spam folder. Fitbit doesn't change your email unless it sends you a verification notice. Someone may have changed the account email address, which means all you can do is start over with a new email address and being the history of your Fitbit.
This copied post is from a moderator and might help you to understand things a bit more.
"An "account takeover", as described in this help article, is a phenomenon that affects many popular online destinations, including Fitbit for many reasons. Fitbit takes very seriously the security of your account and data and my best suggestion is to report any abnormality that you see in your Fitbit account so we can further investigate and help you with that. You can find more information about how to secure your Fitbit account and data here."
Best Answer