Let's make sure you're able to save changes to your email invoices, Jenni5966.

Generally, you should be able to save changes when emailing invoices in QuickBooks since no issues were reported. You can run the Verify Rebuild tool. This will identify any data issues happening within your company file and resolves them after they are found. 

Aside from that, ensure that QuickBooks is up-to-date so you'll have the latest features and product improvements and fixes. However, if you've already done both, but still you're unable to make any changes, I recommend reaching out to our support team. This way, they'll be able to double-check what is happening the second time around. They also have the tools to pull up your account in a secure environment, thus being able to investigate the root cause.

Additionally, QuickBooks Desktop lets you create custom templates for forms and customize them on how they look and what information to include. To know more, I've added this article for your reference: Use And Customize Form Templates. 

You can always drop your reply below if you have further questions about emailing invoices. I'll be sure to help.