To reset your password, first press on the profile picture on the main screen to access the account settings.
Then press on "Reset password".
To set a new password, first enter the existing password and then enter the new password twice and confirm with the "Save" button.
In case you have forgotten your password, press "Forgot password?" below. Now enter a telephone number / e-mail and the new password and press "Get Code". You will receive a verification code which you can enter in the corresponding field. Finally, press "Reset password" at the very bottom.