@PixieRose4 Yes, you can.
1. Go to wattpad.com/myworks then click on the book you're working on.
2. Scroll down to Table of Contents.
3. You will see (three) lines next to each of your chapters.
4. Click and drag on the chapter you want to move.
5. Move it to the desired position.
I hope that clears it up! If not, let me know, and I will send visual guide. :)
~ Stef