I'm here to help.
You can edit the invoice template to add columns.
- Click Lists.
- Select Item List.
- Select the invoice template.
- Right click and select Edit Template. The Basic Customization window will open.
- Click the Additional Customization button. The Additional Customization window will open.
- Go to the Columns section.
- Put a check mark in the boxes labeled Other 1 or Other 2.
- Under the Title column, type the name of the column.
- Click the OK button.
- Click OK to exit.
I've attached a screenshot for your reference.
Should you have any other questions along the way, feel free to ask us here in the Community.