i cannot customize the invoice form

Thanks for sharing your concern and the troubleshooting steps you've made in QuickBooks Community, @abdomunla. 

Let me share additional steps to help rectify the issue and customize your sales forms.

There are times when too much cache build-up in a browser can cause unexpected behavior with the product. This can be the reason why you're getting a blank page when editing the template.

Let's try accessing your QBO account in a private or incognito window. This will help us check if the issue is cache-related and fix it. Simply press the following shortcut keys to access this mode:
 

• Ctrl + Shift + N for Google Chrome
• Ctrl + Shift + P for Firefox & Microsoft Edge
• Command + Shift + N for Safari

Once you're in, customize again your invoice template. If you're able to connect without any issues, go back to your regular browser and then clear its cache and cookies to start over fresh. 

Just in case, I'll add this article for future reference: Import custom form styles for invoices or estimates.

I want to make sure everything is taken care of for you, so please let me know if you have any other issues or concerns. I'm always here to help. Have an amazing rest of the day!

Thanks for Mr, ReymondO 

but still same issue 

really i don't know what its happen first time really since 6 years of using QBO i faced like this issue 

Hi, @Karen. I appreciate you trying some troubleshooting steps to isolate this behavior. I understand that this is a strange experience for you while working with your invoice template. Let me share some information about this issue.

I want you to know that getting a blank/white page when modifying invoice templates from the Custom Form Styles window was been reported to our engineering department. Rest assured they're working nonstop to identify the cause of this error and provide you with a timely solution. While waiting for a fix, I suggest contacting support so they'll be alerted about your experience. From there, they can also link your name to this investigation (INV-84468) and automatically receive email notification of the latest updates.

To contact support:

1. Go to the Help menu.
2. Click on Contact Us from the Search tab.
3. Enter your concern.
4. Choose a way to connect with a live representative.

For your convenience, review the support hours from this link: QuickBooks Online Support.

Once your templates are ready, you can now start tracking and sending your transactions.

Please feel free to mention my name in the comment section below if you have follow-up questions about your forms. I'm always here to help. Have a good one!

I have the same problem on the edition for Latin American and the Caribbean.  The US edition works fine.  What is the problem QuickBooks I just bought the Online Plus Version and have this issue.

Hello there, Dharri06. I appreciate you for joining this thread. Let me make it up to you by making sure you get the best help available so this gets sorted out right away.

Usually, you can easily modify the invoice forms from the Custom Form Styles page. The detailed resolution given by my colleague, ReymondO, above usually fixes these unexpected problems. If you have performed the troubleshooting steps but the issue persists, I recommend contacting our Technical Support Team. One of our experts has the necessary tools to check your account securely and perform a screen-sharing session to conduct further investigation into this behavior.

Here's how you can get in touch with an agent:

1. Log in to your QuickBooks Online account.
2. Click the ? Help button at the top right corner.
3. Go to the Search tab, then select Contact Us.
4. Enter a brief discussion about your concern, then click Continue.
5. Choose a way to connect with us.

Please take note of our business hours to ensure we can attend to your needs.

Additionally, check out these articles that outline how to customize the look of your invoices to match the branding of your company and record invoice payments to keep correct financial records:

• Customize invoices, estimates, and sales receipts in QuickBooks Online
• Record invoice payments in QuickBooks Online

I'm always around and ready to help if you have more questions about managing your sales transactions in QBO. I'll be here to lend a helping hand. Stay safe!