Hi there, Fallon3.

Allow me to share some information about the new designs and how the customization feature for sales forms has changed. 

It's possible that you've been switched from the old to the new experience which explains why your old estimate and invoice layouts are no longer showing.

In QuickBooks Online (QBO), we've recently introduced a new estimate and invoice experience to help you land jobs, keep work moving, and get paid faster.  You'll be able to use the new layout immediately after the update, with no additional steps required. Following the release, you will be able to access all of your previous invoices and estimates.

There are many things you can do with this new experience. And they are as follows:

• Customize estimates and invoices on the spot.
• Get invoices paid faster.
• Get estimates approved faster.
• Track and manage estimates in one place.
• Manage it all on the go.

You can check out this link to learn more: See what’s new with estimates and invoices in QuickBooks Online.

Furthermore, if you still have the old experience but the old custom forms are not showing, we can perform troubleshooting steps by logging in via incognito mode or a private window to check for any browser-related issues.

These are the keyboard shortcuts to open a private window:

• Google Chrome and Microsoft Edge: Ctrl + Shift + N.
• Mozilla Firefox: Ctrl + Shift + P.
• Safari: Command + Option + P.

If everything looks good and you're able to use old custom sales forms, then you can go back to your regular browser and clear its cache. This will remove any outdated and corrupted data that can cause browsing issues.

Alternatively, you can use other supported browsers for a better experience while working in QuickBooks Online.

Feel free to come back to this thread if you still have other concerns about invoices and estimates. I'll be around if you need me.