Thanks for posting in the Community, @comptoisplumbing.
Yes, you can change the estimate into an invoice without retyping everything. I'll give the steps on how you can do it.
After creating and saving an estimate, just click on the Create invoice that will appear beside the total Amount at the top left part.


An Invoice page will appear, you just have to save the invoice. Then it will automatically be linked to your estimate. An invoiced estimate will have an "Accepted" status. If you invoice a full amount, it will set its status to "Closed" automatically. 
For more details about converting an estimate to an invoice, you can check these articles:
Just in case, you'll want to personalize your estimate or an invoice. Check this article on how to customize your sales forms: Customize invoices, estimates, and sales receipts in QuickBooks Online.
Please let me know if there is anything else I can do to help by clicking the Reply button below. Have a great day ahead.