How do i automate not manually, and how i assign piano roll to screen sets

Hitting the W on a track or buss will write enable ALL controls which can be automated, so if you do this, proceed with caution.
 
I find it much easier to right click the control you want to automate and select Automation Write Enable
 
All you do then is play you project and move the control during playback.
You point a will be wherever the control is positioned before playback. You point b will be established when you let go of the control
 
You can easily go edit the envelope afterwards to create smoother curves, get rid of extraneous nodes etc
Don't forget to switch off Write Automaton when you've finished
 
Don't forget there are 3 different automation modes, Touch, Overwrite & Latch which can be accessed under Track Properties > Automation
 
 
Explain what you mean by assign PRV to screensets.

Make sure the Screeset Module is visible in the Control Bar
 
Select any screenset either by typing in a number from 1 - 0 (not the numbers in the number pad - use the numbers on the main keyboard) or by using the dropdown
 
Make sure it's NOT locked (you can verify the lock status from the dropdown)
 
Set it up exactly how you want it then lock it.
 
You can then call this up at any time by using whatever number you've assigned it to.
 
Note that screensets are not global - they are specific to the project.
 
If you're on Platinum, check out the new lenses feature which are global in nature and can do similar things to screensets