If the file has existing lines that are using tabs, then Enter will respect that and try to create new lines in a similar way (see this comment by topchef for a solution). Also, it could be something in Liferay Studio's proprietary settings is overriding Eclipse standard preferences (as suggested by user John).
Keep in mind that each type of editor in Eclipse can have its own preferences and perhaps that's what you're running into here. You can try to find them all by opening Preferences and searching for "indent" in the search field. That will show all the preferences pages where indentation can be configured.
Also note that the Formatter settings don't have any affect on as-you-type formatting; that's for when you select a file or group of files or part of a file and choose Source > Format from the menu.