In order to create custom description in QuickBooks Integration Manager, you will need to follow the steps from below:

1. Launch QuickBooks Integration Manager.
2. Select Client Invoice wizard in the left navigation panel.
3. Follow the Wizard to Map Fields screen.
4. Here you will need to click on the "+" mark under description .
5. This will bring up a new pop up window.
6. Here you can name the description template as per your requirement.
7. You can enter the description and also select the field required for the description.
8. Click on Save once you are done.

Now you will be able to select this description template for creating invoice from the dropdown menu.