Recently, every time I save an invoice, it marks itself as paid. This starting happening about a month ago. Is this an issue within the settings?

Let's turn off the feature to automatically mark an invoice as paid, @sheena7.

QuickBooks Online offers automation features, such as automatically applying payments to an invoice, which can be turned off with just a few clicks from your Account and Settings. Here's how:

1. Select the Gear icon and click Account and Settings. 
2. Select Advanced on the left of the screen. 
3. Click the Pencil icon in Automation. 
4. Turn off the feature to Automatically apply credits. 
5. Click Save and select Done.

See this article for more information on how to create and apply credit memos or delayed credits in QuickBooks Online.

If these payments are creating an overpayment, I recommend the following article which contains steps for what to do: Apply A Credit From An Overpayment.

Should you need additional assistance in turning off this feature, please let me know in the Reply section below. Take care and have a good day!