Printing a invoice

Glad to see you here, @Hollie99,

Yes, there is! You can add this column in the Custom Form Styles window. Let me show you how:

Step 1: Enable SKU columns for sales forms.

1. Click the Gear icon and choose Accounts and Settings.
2. Pick the Sales menu and click the Products and Services section.
3. Turn on the Show SKU column option using the slider. Once turned on, the slider becomes color green.
   
4. Press Save then Done.

Step 2: Enable SKU in the invoice template. 

1. Go back to the Gear icon and choose Custom Form Styles this time.
2. Find the invoice template you're using then press Edit under the Action column.
3. Proceed to the Content tab and click the middle section of the template on the right.
4. Scroll down and tick the check box for SKU.
   
5. Hit Done after.

Once done, you will see the SKU number when you print or preview the sales transaction. See this:

For other options you can do on sales forms, see the following link for reference: Customise invoices, estimates, and sales receipts in QuickBooks Online

Feel free to come back anytime if you have other questions with QuickBooks. I'll be more than happy to help you. Have a lovely week ahead!