Let's resolve your Multi-user mode issue, ivangerasimov39.
This could a be an issue from the program that's why you're unable to switch to a multi-user mode. Let's clean install the program to fix this.
Before doing so, let's make sure that your installation CD and license number are available. Also, you'll need to back up your company file to avoid data loss.
Here are the steps:
- Uninstall QuickBooks Desktop.
- Download and run the QuickBooks clean install tool.
- Rename the installation folders.
- Reinstall QuickBooks Desktop.
For the detailed steps, please refer to this article: Using Clean Install for Windows.
Let me know how it goes by leaving a comment below.