I want to set plugin to display by tag only but I cannot see this option in admin panel
this is my screenshot http://i.imgur.com/ofH3Scf.gif
However, YARPP does have difficulty with languages that don't place spaces between words (Chinese, Japanese, etc.). For these languages, the "consider body" and "consider titles" options in the "Relatedness options" may not be very helpful. Using only tags and categories may work better for these languages.