ok - não tenho certeza se isso é exatamente o que você encontrou, mas tem uma resposta para você - embora não seja o mais fácil de processar:
The Sign Out screen is stored in:
C:\ProgramData\Microsoft\Windows\SystemData\S-1-5-18\ReadOnly\LockScreen_Z
You need to turn on the Show Files and Folders option from Folders
Options in order to see it.
Here's how to change the sign out screen:
go to folder C:\ProgramData\Microsoft\Windows Right click on
SystemData ->Properies->Security->Advanced->Change Enter your user
name (You must be in Administrators group), then click on Check
Names->OK Place a tick on "Replace owner on subcontainers and
objects", click Apply ->OK, Yes->OK->OK->OK
Go to
C:\ProgramData\Microsoft\Windows\SystemData\S-1-5-18\ReadOnly\LockScreen_Z
You will see 2 images of the Seattle Space needle in this folder, To
view these 2 images.
Right click on it->Properties->Securities->Edit->Add Enter your user
name, Click on Check Names->OK->OK->OK
Replace these 2 images with whatever images you want, make sure they
have the same names and resolution as shown in LockScreen_Z.
IMPORTANT: After swapping the images, Right click on
image->Properties->Securities->Edit Make sure SYSTEM is in the user
list with permission shown below: (If SYSTEM is not in the list, you
have to add it to the list using the 2 steps above)
Read&Execute Read
Sign out, you should see the new Image.