There are two different ways to change your password, for email users, you are able to change your password in the bottom left after you login.
When you login click on your name in the bottom left and a menu will pop up, if you control multiple accounts you will have the option to switch accounts.
For Email Users
To change email user password, go to user settings.
This will allow you to change your email and to change your password.
To change username passwords, this must be done by someone with email level access or an account administrator.
Go to settings > Users.
Username users, will show without their email addresses, see the Sam example below. Click on the 3 dots next to their name to pull up their user options.
Underneath their username, click the blue change password option, this will open up a password data entry where you will be able to change the users password.
Make sure you save changes at the bottom of the page.