Can I go back to the previous area? Because I have some achievements that I haven't finished yet. For example, make 1000 cupcakes and 1000 donuts

An Aperitif is a Drink. Not French Fries: https://steamcommunity.com/sharedfiles/filedetails/?id=2728419563

There's a random problem where you cannot deliver when you have a full inventory. The mouse cursor normally brings up a happy face on the customer when you hover over the "Deliver" button. As you can see in the picture below, the customer in not happy. https://steamcommunity.com/sharedfiles/filedetails/?id=2729099176...

how many levels are in the game

How do I move on to new places? I bought the upgrade but there is no option to move on.