If you're referring to Bill expense transactions, the bill marks as Open if you haven't paid the bill. For the Applied status, this happens when you apply for a vendor credit on bills. You can check out this article for more details about supplier credits: Manage supplier credits.
Lastly, it will show a Paid status if you pay bills using either the Pay Bills page or the Cheque page. For more details about bills, please check out this article: How to enter and pay a bill.
If not, please provide us a screenshot on this so we can check it further.
Feel free to reply to this post if you have more questions. I'm here to answer them.