10/7/2025 it happened again that opened firefox disappeared so serahced as:

user accounts popped up 4 which was 2 accounts ie guest and my-user accounts became Administrators, guest, guest-test, and my-user. And also found Administrators auto sigined in.

accidently found out desktop screen also changed and popped up many bookmarks data files, firefox logos and others.

so searched [why my desktop was auto switched to unknown or old time desktop ?] Your desktop is likely resetting due to deceptive software, a dead CMOS battery on your computers motherboard, a Windows time service or Secure Time Seeding issue, driver problems (especially graphics drivers), or accidental user account changes like being logged into a temporary profile.
--immediately assumed [Deceptive Software: Malicious or intrusive software can cause various unexplained behaviors, including desktop changes.] so did MS defender full scan.

in the meanwhile searched [why my pc administrator account auto signed in?] Your administrator account may be auto-signed in because auto-login is enabled, often via the netplwiz command, which bypasses the need for a password, or if you had the last-logged-in account set to auto-login. It could also be a side effect of a Windows reset or OEM installation using default settings for the built-in administrator account.
How to Stop Automatic Login
Open the Run dialog: Press Windows key + R.
Type netplwiz: In the Run dialog box, type netplwiz and press Enter.
Uncheck the box: In the User Accounts window that appears, uncheck the box next to "Users must enter a user name and password to use this computer".
Confirm: Click "OK" to save the change and enter your password if prompted to confirm the operation.
Restart your PC: The next time you restart, it will require a password to log in. --which i have no confidence. so searched [disable builtin administrators account will stop my desktop auto switched different screen?] No, disabling the built-in Administrator account will not stop your desktop from auto-switching screens; this issue is typically caused by problems with graphics drivers, user profile corruption, or incorrect display settings, not the built-in Administrator account. You should instead focus on updating your graphics drivers, checking your user account settings, and disabling Fast User Switching via the Group Policy Editor

searched [how to disabling Fast User Switching via the Group Policy Editor]
To disable Fast User Switching via the Local Group Policy Editor, open gpedit.msc, navigate to Computer Configuration > Administrative Templates > System > Logon, and then enable the "Hide entry points for Fast User Switching" policy. This will hide the "Switch user" button, preventing users from switching accounts without signing out
Step-by-Step Guide:
Open the Run dialog box: Press the Windows key + R on your keyboard.
Launch the Group Policy Editor: Type gpedit.msc into the Run dialog and press Enter or click OK.
Navigate to the policy: In the left pane of the Local Group Policy Editor, expand the following path:
Computer Configuration
Administrative Templates
System
Logon
Edit the policy: In the right pane, find and double-click the policy named "Hide entry points for Fast User Switching".
Set the policy to Enabled: In the policys properties window, select the Enabled radio button.
Apply the changes: Click OK and then close the Local Group Policy Editor.
Restart your computer: A restart is required for the changes to take effect.
Verification:
After restarting, check for the "Switch user" option on your login screen or in the Start menu to confirm it is gone.
--so i did Enable "Hide entry points for Fast User Switching" but found the MS defender full scan screen disappeared or else. cant but restart my PC.

then the screen showed up the auto changed desktop and found my 360doc also was old version (till 9/28/2025) ie my updated in Oct all added 随笔 (and 文章?) lost. PS correct: found it on [美国“战争部”急颁全球召集令，要有大事发生？...] 12 hours ago [激烈对峙！美抗议者与执法人员在芝加哥爆发冲突，...] that is good news. but also bad news cant explain why file explorer data files frequently disappeared but quite sure caused by file explorer switched to different version and some data files after saved unknown disappeared but few didnt.

How to Disable Administrator and [Why You Should]
Use the Command Prompt:
Press Shift + Restart to access the Windows Recovery Environment.
Select Troubleshoot > Advanced options > Command Prompt.
Type the command net user Administrator /active:no and press Enter. PS didnt know [Press Shift + Restart] but below 8. searched [how to disable builtin administrator account?]
Close the Command Prompt and restart your computer.
Why Disable It: Disabling the account makes it inaccessible for potential attackers, even if they somehow gain administrator access
Side Effects to Be Aware Of
Your Accounts Privileges: Your user account being in the "Administrators" and "Users" groups grants you all the privileges of an administrator. This is separate from the built-in Administrator account and does not cause interference.
Potential for Conflict with Deny Permissions: If any "Deny" permissions are set for your user, they take precedence over your "Allow" permissions, which can prevent your administrator-level access to certain resources

searched [how to disable builtin administrator account?]To disable the built-in Administrator account, open an elevated Command Prompt or PowerShell, then run the command net user administrator /active:no -- PS C:\users\my-user-name >net user administrator /active:no
The command completed successfully.

or Disable-LocalUser -Name Administrator, respectively, and press Enter to immediately disable the account.
PS i am not so sure the above really can stop auto switched desktop different version or not. wait to see ....based on my horrible experiences that any solution to solve MS updated caused serious problems wont last longer.

更新 10/7/2025: just remember that before disable builtin administrator account, must change or add new user account which has administrator 特权 otherwise some system related command cant perform when needs. Another way is enable/recover by :
PS C:\users\my-user-name > net user administrator /active:yes
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