Every time I send Invoice to a customer its saying its been paid, how do I stop this happening.

Thank you for bringing your invoice concerns to the Community, enquiries-birchw.

It appears that the Automatically apply credits function is enabled based on the information provided. When you activate the feature, it automatically applies credits to the next invoice you create for the same customer. If the credit matches the amount on the sales entry, the credit note and invoice will show as Closed and Paid.

To resolve the issue, we'll need to go into the Advanced settings and deactivate Automatically apply credits. I'm here to guide you through the steps on how to get there:

1. In your company, tap the Gear icon in the upper-right and choose Account and settings under Your Company.
2. Go to the Advanced menu on the left panel to see if the Automatically apply credits status is set to On. 
3. We'll have to turn it off if you want to decide which open invoices you want to apply credit memos to, simply move the slider to left to deactivate it.
4. Click Save and Done for the changes to take effect.

I've included a link to an article that describes what happens to invoices when the feature is enabled: Create and apply credit notes or delayed credits in QuickBooks Online. From there, you'll learn when to use credit notes and delayed credits.

Could you send a screenshot of your concern if the Automation settings are set up correctly? This will help us determine why it says that the invoice is already paid.

For future reference, you can save the link to the Community page. From there, you'll find topics, resources, as well as answers to accounting-related tasks. 

If you have additional questions about invoices or other customer-related concerns, drop a comment below. I'll jump right back in to answer them for you.