There are two ways to change the password for personal account
First method
When you logging to Personal Account, click «Forgot your password?» button and enter your email, to which you will receive further instructions on changing the password.
Second method 
1. Login to Personal Account,
2. Go to Details section. To do this, click on the mail in the upper right corner of the interface,
3. Click Change Password button on Details tab,
4. Fill in Current password, New password and Re-enter new password fields,
5. Click Save button.