"Single-User Mode" is one of two conditions under which QuickBooks allows you to log in - the other being "Multi-User Mode". There are many functions that QuickBooks will not perform unless it is in Single-User Mode, because this prevents other people from manipulating data while important processes are being performed.
Switch to Single-User Mode:
- Have all users log out of QuickBooks except for you.
- Log in (if you are not already logged in).
- Go to File → Switch to Single-User.
QuickBooks will close all open windows within the program and then a message will appear letting you know that QuickBooks is now in Single-User Mode.
To switch back into Multi-User Mode, go back to File → Switch to Multi-User.