There are four following colors of folders and layer in each .psd file:

1. Red		- smart-object with the 2880x1800px screenshot
2. Green 	- folder with all box's layers
3. Blue 	- folders with display's (closed/30/90/110)
4. Yellow	- folder with the shadow and reflection



To change a angle of the display in one of the source (e.x. 2.Macbook - front views.psd)
you just need to turn on 'Display-90' folder and turn off 'Display-30'.


There two ways to replace the original screenshot on the display with your own. 
Your own screenshot must be 2880x1800px size.

First one:
1. Open one of the .psd files in the Adobe Photoshop.
2. Right-click on the red 'Replace the Screen' layer.
3. Select 'Replace Contents'
4. Choose the image file on your computer.

Second one:
1. Open one of the .psd files in the Adobe Photoshop.
2. Double-click on the thumbnail of the red 'Replace the Screen' layer.
3. Drag & drop your own screeshot into opened smart-object or paste it from the clipboard.



To upscale or downscale one of the views then just press 
ALT+CTRL+I (ALT+COMMAND+I), set the desired size and press OK.
The rest will be done automatically without loss of quality.