sir..
I am using kdenlive 19.12.3 and I enabled snap option and also enable project monitor grid view by changer overly button... but when I drag any clip-on monitor, snaping is not working for me. and when I drag by using transform effect grid system automatic disable...please help me

Snap doesn't work to a monitor overlay (Do you mean that?). Grid disable by adding an effect is a bug which should be solved in 20.04.