Hello,, I'm Greg, 10 years awarded Windows MVP, here to help you.
What exactly popped up that you thought was an Administator account? Can I see a screenshot of it?
If this is your PC why are you not running an Administrator account which is what Windows creates when you install it because it assumes you're the owner. There is NO good reason to not run an Administrator account, the same warnings given when changes are attempted are flashed to all accounts via UAC, Admins just have a Yes button to approve the while Standard Users must put in the Admin password.
To turn off System Preparation tool from popping up when WIndows starts:
https://www.techyv.com/questions/fix-system-pre...
Check in Settings > Accounts > Your Info if it says you're running an Admin account. If not see if you can change to an Admin account one of these ways:
https://www.digitalcitizen.life/change-type-use...
If not is there another Admin account you can sign into to do this? If not then I'll need to help you unhide the built-in hidden Admin account used in emergencies to do this. This might also be needed if your account is corrupted which the condition can mean as explained in the tutorial about disbling SysPrep.
Based on the answers you post back I may have other suggestions.
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