When you're logged in to your Vimeo account, you can update your password at any time by following the instructions on your Password Settings page.
If you're not logged in your to your account, you can fill out this form in order to reset your password.
When resetting your password, you'll receive a password reset email within 2 minutes. You'll have to click on the link in the message in order to choose a new password.
Please note that trying more than once to reset your password generates multiple emails, and only the last one sent will contain a valid reset link.