Changing Password In-game

Go to the quest tab, while under the help desk, scroll down and look for the Change Password.

This shows up:

You have easy, medium and hard passwords, just type the password and see what it says.

(easy)

(medium)

(hard)

If you are 100% sure on what the new Password has to be, then Click Change.

If you clicked Change, the new password shows up in chat.

Changing Password On Forums

You must be logged on your forum account. Click your name on the top left and select account settings.

Hover over to Password and type in your current password and your new password twice.