I wonder if there is a way to change the minimize / restore / close buttons
The visual styles i have are OS X. I searched everywhere but couldn't find how to change them. They look like in the image nr 1 ( round )
And i would like to have them like in the image nr 2 ( square )
Would you help me with some advices, please ?
Thank you

https://postimg.org/image/yujtrtl89/b2cff5bc/

https://postimg.org/image/psfz52s17/d5704f0e/