Thank you, Wolfshadw.
It is shown in Display Properties/ Setting Tab / Screen Resolution.
The resolution setting slider 'Less-More' shown that the particular monitor is 1920x1080 at full right position while the other monitors still have more resolution beyond 1920x1080, that is: 1600x1200, 1920x1200, 1792x1344, 1856x1392, 1800x1440, and at full right 2048x1536. All of these resolutions are really functioning although some of them were not well fit.
So far I keep the 1920x1080 for all monitors (I rotated my screens 90° so they are in 1080x1920). I think I'd better neglect this little problem as per your suggestion but still wondering about it.