Can you please advise how I add an additional column to my invoices?

Hi there, @accounts-medifor.

Being able to add custom columns on sales forms would be a great option. Rest assured that I'll relay this message to our team in concern here on my end and add your vote for this one.

You can also share your thoughts and ideas through your account. Our product development team reviews all the feedback we receive to ensure we’re meeting the needs of our customers. 

Here's how:

1. Select the Gear icon at the top, then Feedback.
   
2. Enter your comments or product suggestions then select Next.
3. You'll be provided a list of suggested Help articles related to your comment. You can read through them or select Skip and send message.
4. From the drop-down, choose the appropriate category, then select Send message.

For your reference, check out this link: How to Submit Feedback. 

We also share recent happenings and future developments, such as updates to newly added features. Head to this link: The Firm of the Future.

Drop me a line if you need more help with customising your sales forms in QuickBooks Online. I'd be happy to assist you. Thanks again for reaching us and have a great day.