Please!
Update: Thank you for reaching out to me. I finally figured it out. I absolutely love this app!!!
Response from developer
The “Paid” button is for bills. If the item has no price, it’s considered a task and it gets the “Done” button. Including a price, even if it’s $0.00, will change to button to “Paid”. If you’re still having a problem, please send me an email at pete.lewis1@icloud.com. Sorry for the delayed response. I only just saw your note today.