How do I change the login screen image displayed after a reboot on Windows 10?

Question

In Windows 10 it's easy to change the lock screen background image in Settings > Personalization > Lock screen. I have it set to Spotlight for my account. When I log out it displays the same thing it does when I lock, i.e., it displays my Spotlight. Presumably this is because I was the most recent person logged in.

However, after a full reboot no one is the most recent person to log in, and it does not display my Spotlight or any other image I select in Settings > Personalization > Lock screen. What it displays is one of the human-in-nature images that ships with Windows 10. In my case it's the one with a mountain lake and a red backpack in the foreground.

I really want to change this image. How can I do that? Does anyone know if this image is configured in Settings > Personalization > Lock screen of some other account, such as a local administrator account or some such? I have admin privileges on this machine but don't have the password to the local administrator account.

Update 1: Marcus's solution worked at first. When I rebooted it used the picture that I chose. Awesome! But then when I turned Spotlight back on and rebooted again it went back to the prior lake+backpack picture.

I got access to the local Administrator account and set its lock screen to Picture. Turns out that the image displayed right after boot IS determined by the last user to be logged in before the reboot. When Administrator was logged in and I reboot it shows that account's Picture. And even if I switch Administrator's lock screen to Spotlight it will show the Spotlight image after a reboot. After a reboot it will only show the Spotlight image, though, not the click-bait text regarding the image.

The problem seems to be specific to my account. Spotlight doesn't operate immediately after the reboot if I was the last user logged in. It instead deploys some fallback image. Does anyone know where that fallback image is stored? I could just replace it with an image of my choosing and give it the same name as the one I don't like.

Answer 1

Although Windows is constantly changing, here are a couple of solutions.

Group Policy

Run the Local Group Policy Editor (gpedit.msc) and position to Computer Configuration > Administrative Templates > Control Panel > Personalization. Set "Force a specific default lock screen and logon image" to Enabled, enter the path to the image, and click OK.

Registry

Use regedit to navigate to the key HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Personalization. If the subkey Personalization does not exist, then create it. Create a New String Value named LockScreenImage and set it to the full path of the image.

Answer 2

Try the following:

1. In Start > Personalization >Lock Screen, change Background to Picture, but do not exit Settings
2. Delete everything inside:

   %LocalAppData%\Packages\Microsoft.Windows.ContentDeliveryManager_cw5n1h2txyewy\LocalState\Assets\
   

3. Rename settings.dat and roaming.lock to settings.dat.bak and roaming.lock.bak within:

   %LocalAppData%\Packages\Microsoft.Windows.ContentDeliveryManager_cw5n1h2txyewy\Settings\
   

4. Reboot

This might also be of use to you:
Win10 "spotlight" lock screen was stuck on single image, now blank and no image ever gets displayed