Adding corners is a little bit more work. Don’t get me wrong, it’s just as easy but there is a little more involved. To add the corner you do the same steps as before, by clicking the left option on the grid and choose corner. Once you choose the type of corner you want, choose which corners you want and click on them.
You can either choose radius or clip corners.
Changing Corners from Panel / Deleting Corner
You can change this later by looking to the right on your panel and change it or delete it by choosing the corner option there.