Need Urgent Help Please

[Johnny Boy]

Guys here's my problem

I have been following this tutorial in the following link below:

https://www.youtube.com/watch?v=3Rc0dNDzbuM&t=466s

But when I got to 6:57 and tried to increase the brightness in my own file, only the glitched screen in the split screen by the right was brightening up but the logo by the left wasnt.

Here is a copy of my project here. 

https://takeafile.com/?f=yigufineje

Need urgent help to diagnose the problem to proceed

I want both screens to brighten up when I increase the Brightness value on the left panel.

In my case, only the right one is getting bright...

Please

Thanks