Multiple Document Interface is not working correctly. When I click the button to switch to Multiple Document Interface, all the open windows switch to not maximized, so when I click on one of them to maximize it converts back to Single Document Interface. I want to get rid of the tabs across the top.

You can go to Preferences > User Interface > Appearance and set the "Settings for Single Document Interface" to "Don't show tabs".

Did not know that was there. Thanks!