SOLVED! - Why Windows Search for Words Only in Filename, not Content of the File

Many Windows 7 users are very confused of the built-in search function on Windows Explorer. At the top right corner of your Windows Explorer is the Windows Search, but why typing a keyword shows only filenames with the keyword!??

For example, when you want to search a keyword like "Mary" in a Microsoft Word document, instead of just typing "Mary", you should type as "content:Mary".

Other filters follow this syntax, such as kind:, type:, datemodified:, size:, etc. Also when available, drop-down list will be shown for your convenience.

However, the found "keyword" is not highlighted as in the case of Google Desktop, which has officially stopped by Google...too bad.