Hello there, @AM71.

Let me help you make sure your QuickBooks Desktop (QBDT) is set up on a multi-user network so you can access your company files from other computers.

Before we start, please know some of the reasons why the multi-user mode feature isn't working in QBDT:

• QuickBooks is not installed on the server
• Possibly that the hosting settings are not properly configured
• Firewall or antivirus software is not allowing communication between users' computers
• The database server is unable to open the company file
• Windows file permissions are not properly set

To fix this, you'll first need to check the folder permissions on your server computer. This is to make sure the folder holding your company files has permission to be on your network.

Next, make sure that the QuickBooks Database Server Manager is installed on your server computer. This way, you can share your company files with other computers over your network.

Then, set the Windows admin rights to permit you to make changes to your firewall settings and folder permissions and scan your folder using the Database Server Manager to access your file over the network.

Once you're done, you'll have to turn on hosting on your server computer. For the complete guide, I'd recommend checking out this article: Set up a multi-user network for QuickBooks Desktop. 

Also, you may want to visit this article if you wish to learn more about the tasks that you can perform in a single or multi-user mode in QBDT: Features available and tasks you can perform in a single or multi-user mode in QuickBooks Desktop.

Please keep me posted on how it goes in the comments below. If you have other concerns about multi-user mode in QBDT, I'm always ready to help. Take care, and I wish you continued success, @AM71.