When you first turn it on you are using the scratch pad row. It is indicated by two underscores in the bottom left hand corner of the display. When you change patterns you will see the pattern flash to the right.

Press Function + Song/Edit and you enter the screen that allows you to edit chains and songs. Press Function and Chain/New to start a new chain.

I can’t remember the exact keystrokes and I am struggling to understand it myself so I can’t be more help than that at the moment.