Step 1. Please click http://mail.gs.ncku.edu.tw , enter account / password.
Step 2. Click on the 'Settings' button on the top right and click 'See all settings'.
Step 3. Click the 'Accounts and Import' tab, choose the main account and click 'make default'.
Step 4. After clicking, the alias will be set as the default account when replying to a mail.
Step 5. Click on 'Compose an email' on the top left.
Step 6. The default sender has been set as the account that chose in Step 3.
** If there are other needs, you can also drop down the menu and change it to another account.