Hi!
All levels are solveable, I tested them personally (and repeatedly), and had them tested by different people to make sure. Later levels are a bit harder, so it's easier to get stuck. Don't give up, you almost made it to the end!
Edit: I just now realized you might have been asking for a hint. Sorry, English is not my first language. Another user (gencivl) posted a useful video that can help you.