Method 1
• Right Click 'My Computer' / 'My PC' / Computer (depending on the version of Windows
• Select Manage on the menu that pops up
• Go to 'Local Users and Groups' and go into 'Users'
• Right-Click the user you want to change and go to properties
• Go to the "Member of" tab, and click Add
• Add 'Administrators"
Method 2
• Go to Control Panel (Change the view to 'Small Icons')
• Go to 'Users and Accounts'
• Select 'Change your Account Type'