How do you set xy zero

So brand new to Inventables and Easel. My question is how do you set the xy axis to zero? Does where you set the material matter when setting them to zero? Do you have to home the machine every time? I had to change a bit today because the rough out didn’t finish the carve and when I did, I accidently jogged the machine an inch to the right and wrecked my carve. Any help would be appreciated.

The x and y zero are set when you click carve and begin the sequence to setup the carve…

In the design screen the x,y origin is always the lower left, where 0 and 0 meet