Thank you for your prompt reply.
To reproduce the issue:
In the online address book > right click on a remote machine > Properties > Color and CPU >
I can only set the color format and CPU usage and save. The FPS value 15 is gray and i cannot set the FPS here.
What I have to do is: Double click the online machine in full control mode > In the control windows > right click > Properties > Color & CPU > set the FPS to 1 > Apply & OK.
Close the control windows and then re-connect again the same machine, you will find that the FPS is returned to 1 again.
Thank you for your help in advance.