(1) Open Internet Explorer.
(2) Select TOOLS >> INTERNET OPTIONS >> SECURITY Tab.
(3) Choose the “CUSTOM LEVEL” button.
(4) Within the Settings change “USER AUTHENTICATION” to “Prompt for user name and password”
(5) Choose OK >> APPLY.
(6) Close Internet Explorer.
The next time you go to log into CRM via the Internet Explorer, you should be prompted to enter in your username and password.