For a lot of people, Outlook is the preferred software for looking at email and storing it. The format is something people like. Setting a third party email, such as Gmail, can be configured so you get the ease of Gmail and the structure of Outlook. What happens when you need to change your password?
Since you are using a third party email, you will need to go to that email site. In this case, go to Gmail web interface and change your password there first. You can click on the account name icon, usually the first letter of the signed in user, and click on Manage Your Account. Click on Security, on the left side. Then click on Less Secure app access to make sure it is turn on. Outlook is considered a less secure app by Gmail.
Scroll up a bit and click on the Password link, (arrow), under Signing into Google. Change the password there. You will need to re-enter it to access the portal. Then enter the new password.
Next go to the Control Panel and click on the Mail icon, click the first option for Accounts. Highlight the account to change the password for and click Change at the top. Enter the new password where indicated.