I cannot edit departments?

Hello there, @rick75.

Thank you for adding a post here on the Community page. I can share with you some information about departments and classes in QuickBooks Online (QBO).

Editing departments depend on how you set them up in your account. Usually, classes or location is used for this purpose. For QBO Plus subscription, you'll be able to create up to 40 classes/locations and no limit for QBO Advanced. Since you already know how to manage classes, I'll be sharing with you on how to edit the locations added in QuickBooks.

Here's how:

1. From the Gear icon, select All list under the Lists menu.
2. Tap Locations.
3. Look for the location you want to edit, then select Edit under the Action's drop-down arrow.
4. Modify the information from there, then click Save.

To learn more about these features, feel free to read the details from these links:

• Turn on class tracking in QuickBooks Online
• Get started with class tracking in QuickBooks Online
• Set up and use location tracking

Besides, you see the usage limits of your subscription from the Accounts and Settings page. 

1. Tap Accounts and Settings from the Gear icon.
2. Go to the Usage tab at the left pane.
3. Review the information under the Usage limits window.

On the other hand, if you're using the project feature, you can learn more of this from this article: Set up and create projects in QuickBooks Online.

I'll be right here to continue helping if have any other questions. Just add a comment below. Have a great day!