start a cmd.exe (admin if you can not required if you don't make changes to the info via this interface)
then type
net.exe user (this will show the names of the users for the machine)
whoami.exe (will show the name of the current user)
net .exe localgroup administrators (will show the names of the admins for the local machine)
if you changed ownership or reinstalled then the documents directory will belong to a different SID even if you used the same name.
fixing that requires a different command (i will see if i can quickly look it up. I always forget the it)
the command is icacls.exe
to see who has rights to your directory you would
start cmd.exe as an admin (if you want to make changes)
then run
icacls.exe c:\users\myaccountname\documents
and it will return something like this
C:\Users\Cloud\Documents>icacls c:\users\cloud\documents
c:\users\cloud\documents NT AUTHORITY\SYSTEM
I)(OI)(CI)(F)
BUILTIN\Administrators
I)(OI)(CI)(F)
BIGGLASSDOG\Cloud
I)(OI)(CI)(F)
this shows on my machine that the built in administrators group has full access (F)
and the local account called Cloud on the machine BIGGLASSDOG has full access
whoami i shows that my login name is being mapped to the local account Cloud
even though I am logged in to a microsoft email account. I think the mapping was done when I did text verification from the microsoft account that I owned this machine.
you can run
icacls.exe /? to see all of the options and how to grant permissions to specific accounts/people or a particular SID