HOW TO CHANGE all THE INVOICES TO OLD STYLE AND NOT MODERN

We can modify the invoice style setting to set up forms for window envelopes, Kylahzarate. I'll provide information when managing customer sales transactions in your QuickBooks Online account.

As QuickBooks aims to provide enhanced layout preferences and satisfaction to product experiences when performing sales entries, reverting invoices from the new form layout to the old template is unavailable in the program. Feel free to visit this resource for additional inputs: See what’s new with estimates and invoices in QuickBooks Online.

In addition to that, you can set up your forms to print invoices for window envelopes from your account's settings. To do this:

1. Go to Settings ⚙ and select Custom Form Styles.
2. Choose an invoice form, then Edit.
3. Under the Design tab, select Edit Print Settings. 
4. Put a check on the box before the Fit to window envelope.
5. Review other details and click Done to save.

Then, go to your open invoices and refer to these steps to guide you in setting up sales form template settings:

1. Go to Sales and select Invoices.
2. Choose an invoice and click Edit from the Action column.
3. Under the Manage section, click Design.
4. If the Modern option is enabled as a default setting, tap Remove Default and choose the specific invoice layout you modified from the above steps.
5. To verify the setup, click on the Print and Download option below.
6. Once done, hit Save and Close.

Once everything looks good, you may want to track and enter customer-paid invoices and run specific reports to help review your business finances.

I'm always available in this thread if there's anything else you need further assistance with when managing sales entries in your account. Just keep me posted, and I'll be around to provide additional help. Stay safe and have a great day ahead!