This sounds a lot like User Account Control, something Microsoft introduced with Vista. Even with a user being an administrator it will still prevent you writing to (I believe) non-user filestore i.e. C:\
Its purpose was to increase security for your PC but those upgrading from Windows XP soon found it to be a real PITA. You could disable UAC in Vista through Control Panel and it can also be disabled in Windows 10. However, with Windows 10 if you do disable it then you will find that Windows apps will no longer run because, as it tells you, UAC is not enabled.
This is why I regressed to 8.1, where UAC did not seem to be running as I was able to use the system as I could with XP i.e. no restrictions.
The kicker is that when I regressed to 8.1, write access to C:\ was still not allowed. Thanks Microsoft.
I am not a scientific computer guru so please pardon any spelling errors or information I provide. But I had this problem too and was Very close to becoming an Apple user. HOWEVER I have resolved the problem and partly from what I read here.
In the file explorer, right click each file (Pictures, Documents, Music ect) This brings up the properties menu. Click the security tab and click (highlight) your user status. Administrator it seems has full permissions but local user (Also myself) did not, So by click on local user and editing permissions giving myself full permissions then hitting apply (And yes getting an error message) Click yes, continue whatever about ten times and you should see the PC changing permissions in the root. Do this for each folder in the file explorer then reboot. After re-boot verify that you're changes have saved and create a restore point.
Now go back to C drive (Assuming C is your HD) and right click go to properties, Security and you should see permissions for the users and administrators. If not change these here too. I actually did this first.
The result is that I now have re-gained full control of my PC .... Well I hope so at least ...
Hope this helps.
Thanks for the info nctxscanner, I will try that.
I know that I'd read on these forums from another user that had this issue and of course others like myself that told the person that they can run windows apps fine with UAC turned off/disabled.
I tried that, but after rebooting my Security settings went back.
I was unable to save files to the My Documents folder
Having read the above threads, in particular the response by Brink
Owner of Files and Folders - Change in Windows 10
Look at Option 4, step 5
You can see the owner is TrustedInstaller in his screen capture
On my PC the top level C:/ folder also had this ownership set. Probably the Windows 10 installer changed the ownership to TrustedInstaller. (If I were to go back to Win8.1 I suspect that the ownership would remain set to this.)
When I changed the owner to Administrators everything was OK. No other changes necessary
Thanks to all for the contributions
You can change the security settings in a number of ways to get around this.
Is it still a problem?
When you log into your machine, does it show your account name or an email you use for a microsoft account? If it shows the email try the following steps:
1: log in normally.
2: press start -> click on your email/account name at top left of start menu (might be a right click, not 100% sure)
3: select "sign into local account"
4: if it doesn't auto log you out, log out, and you should have a local account name on the log in screen.
5: log in, and see if the problem is solved.
It's a problem with file ownership. the local account owns the files, but not the microsoft account. So even though both have admin privileges, it creates access problems. Another solution is to change the file ownership to the admin group. (my IT teacher just did this, but I cannot recall the steps he took.) That way both accounts have access since they're both in the admin group.
EDIT: Found it, he did option 4 from this link that several others have linked in this thread: Owner of Files and Folders - Change in Windows 10 - Windows 10 Forums