Glad to have you here in the Community, @evista_michelle. 

I appreciate you providing a screenshot for me to get a better picture of your concern. 

Yes, you can manually enter activity updates on the invoice. However, please make sure not to click the Save and send button at the bottom of the invoice after saving it. This way, it will not be sent to your customers from the program. 

You can choose Save and new if you wish to save your work and create a new invoice. Select Save and close to save it and close the screen. Just click Save if you want to save the changes without leaving the invoice.

Please see the screenshot below to serve as your visual guide. 

Please check out these helpful articles to learn more about managing your customers and income in QuickBooks. 

That's it, @evista_michelle. Feel free to reach out to us again if you have any other concerns. I'll be here to help.