Page cached by proxy

If I maintain my site in University library, the pages including admin pages would be showed the previous after click “update” and click on the page again. but the database was actually updated correctly.
However, the operation is fine in my home. So, I believe the reason should be from the proxy of the University. Other web sites didn’t show this problem.

The case is also in the support site. When I just registered here, I got the password from e-mail. Then, I login and the page is still showed the input box. I tried a few times. After taking some food, I found I got login here.

Is there a setting I missed or anywhere I can check?