I do not think blaming support for lack of basic skills with the product is fair. Also, configuration change does not qualify as support issue. The answer you received is adequate and goes even beyond your support contract.
To help you out, some more information is required.
1. SmartConsole can be used by multiple users. Which account password do you want to change?
2. When configuring R80.10 Management machine, what has been set for the default admin account? Are the credentials of "admin" account reused to access SmartConsole?
If the answer to p. 2 is yes, you may want to change Gaia OS admin password as well. Vladimir Yakovlev has already told you how to do that. You need to:
a. open ssh session to the machine and login as admin.
b. run the mentioned command: set user admin password - and change the password.
c. after changing password run "save config" and exit ssh session.
That will change both OS and GUI admin password.
In general, please consider taking some courses on Check Point products. Standard CCSA R80.10 course will help you enormously.