Hi Stacey,
First, you must go back into Single User mode first. *Please do an external backup if possible, first, and use the following steps with care:
1. Restart your Mac in single user mode:
* (Command - S after powering on)
Continue holding the keys until you see
white text on the screen.
- If you're using FileVault, release the keys when you see the login window. Then log in to continue startup in single-user or verbose mode.
- If you're using a firmware password, you must turn off the password before you can start up in single-user or verbose mode
2. When the terminal prompt appears, you will
enter the following commands. After every
command press enter:
- mount -uw /
- rm /var/db/.AppleSetupDone
- reboot
3. This will allow you to go into setup assistant, and you can then set up an administrator user. After, you can then change your standard user as an administrator.
Please note:
After you reboot the computer and you are taken to the Setup Assistant, there will come a point in which a prompt will ask you to set up your new user account. This is where you create a new admin account.
*****IMPORTANT: Be sure to name this user account something different than the admin user account that already exists on the system.
When you finish the Setup Assistant, it will automatically log you into the new account.
If setup assistant does not initiate as happens in many cases specific to this, then you would force initiate it to begin setup assistant