1. On your computer, open Gmail in web browser.
2. Make sure you are logged into your UCSD Google account (check the logo in the upper left).
3. In the top right , click gear > Settings.
4. Click the Accounts tab.
5. In the "Send mail as" section, to the right of the email address you want to use, click make default.
If you use Thunderbird or other email clients and wish to always send email from the alias, select the option for "Always reply from default address".