For the safety of your Fitbit account, it’s better to change your password from time to time. That’s why we explain with simple steps how to modify your password using a desktop computer:
 1  Open Fitbit.com
 2  Enter your email address and password
in order to log in.
 3  Choose Settings
after clicking on the gear wheel in the right top corner.
 4  Change password
is a blue link that you find next to the Email address field.
 5  Enter your current password
followed by the new password that you want. Click on Change password when you’re done.
 ✓ Result
Once you click now, your password will be modified immediately.
Source screenshots (& thanks to): Fitbit.com