Lightroom Develop module tone settings

Hello sir, 

Greetings of the day,

I have seen my friends editing their photos on lightroom with just the mouse cursor kept on name of the adjustment like (eg. highlights, shadows) and incresing or decreasing with the help of keyboard keys plus and minus (+,-). But when I do in my system it doesnt happens, i have to click on the shadow then it says modifiy shadows with  +/- keys. then only I am able to do..

How to change without clicking on shadows or other tone internal settings , 

Please do reply

 Thanks