Ubuntu allows users to change the password using the Control Center. To change the password, launch the Control Center then click to About Me under Personal section.
The About me screen can be used for setting personal information and it looks as shown below.
Click the Change Password button available at the top right corner of the About Me page. This would display the following Change password dialog.
Provide the Current Password and then New Password and click Change Password button to change the password for a user in Ubuntu