I can help you enable the Advance Inventory Settings, Handeholder.

You need to turn on this before before proceeding. And, I'm here to provide the detailed steps;

1. From the Edit menu, select Preferences.
2. On the left pane, choose Items & Inventory then go to the Company Preferences tab.
3. Check the Inventory and Purchase Orders are Active box.
4. Select the Advanced Inventory Settings button. 
   

If the button is grayed out even though you have purchased the feature, you will need to sync license data online so that QuickBooks recognizes it. Here's how:

1. In QuickBooks, select Help then Manage my License and then Sync License Data Online.
2. Check that Advanced Inventory Settings is no longer grayed out.
3. Close and re-open the QuickBooks program.
   
   

If syncing fails, download and install the QuickBooks Tools Hub to help fix common errors. For the best experience, we recommend using Tool Hub on Windows 10, 64-bit.

1. Close QuickBooks.
2. We recommend you download the most recent version (1.4.0.0) of the QuickBooks Tool Hub. Save the file somewhere you can easily find it (like your Downloads folder or your Windows desktop). Note: If you've already installed Tool Hub before, you can find out which version you have. Select the Home tab.  The version will be displayed on the bottom right or you can select About to view the version.
3. Open the file you downloaded (QuickBooksToolHub.exe).
4. Follow the on-screen steps to install and agree to the terms and conditions.
5. When the install finishes, double-click the icon on your Windows desktop to open the tool hub.
   
   

Once done, run the Quick Fix my Program to shut down any lingering background processes QuickBooks may be using. 

1. In the tools hub, select Program Problems.
2. Select Quick Fix my Program.
3. Select the QuickBooks Program Diagnostic Tool.
   
   

Let me know how this goes by commenting below. I'm always around to help you.