I have a password protected admin account which is not used itself, it was created for a security reasons. Practically my computer is used with a second password protected standard user account. When I'm trying to execute some task which require admin rights, I receive an UAC prompt where I have to enter the admin password. Problem is that I still can run task manager without an UAC prompt, which is seems incorrect because the UAC level is the highest possible and the account have no administrator rights, I also think is't bad for system security. Can I fix it?
You don't understand what highestAvailable means.
highestAvailable means the application gets the highest privileges according to its group membership, so it will elevate (UAC dialog) if the current user is a part of the administrator group. When a standard user runs the process, no UAC dialog is shown and the process runs with the standard permissions and displays less data. This is what you see.