As long as you have access to your account and remember your current password, you may change the password at any time by following these steps:
- On the main game screen, scroll the bottom menu to the right side to the option "Settings"
- Tap on "Change password" in the first tab
- Enter your currently used password in the first box and the new password in the second box
Once confirmed, the new password should be set for the account immediately.
If you forgot your current password and need to reset it, please check the following article: