How can i?

[postacini]

I dont want to change materials..Just i want to paint.Actually i dont like this...It's very useless.. 

[JeffM]

"Applying" a material in KeyShot 3 is the same thing as "painting" a material in KeyShot 2.

[postacini]

Not same..When i change material Keyshot 3,all is changed..But Keyshot 2 is different..Keyshot 2 just a one material changed.

[Speedster]

I think you may be referring to the materials being "linked"?  That is, multiple surfaces or parts behave as if they are one.  If this is the case, you can right-click on a material and select "unlink material".  I have noticed in KS3 that at times a model will inport with funky, or odd, material linking that was not intended in the native CAD.  I believe this is being worked on.
Bill G

[postacini]

I think you may be referring to the materials being "linked"?  That is, multiple surfaces or parts behave as if they are one.  If this is the case, you can right-click on a material and select "unlink material".  I have noticed in KS3 that at times a model will inport with funky, or odd, material linking that was not intended in the native CAD.  I believe this is being worked on.
Bill G

Very late but this is correct answer,for my ask..Thank you Bill..