Insert staves

Hello,

As you can see in the photo, you first see a staff that consists of 2 bars (above a big black line). Below that you see a staff that consists of 3 bars with also a big black line.

If I want to write a piece of music, I have to choose between either the entire piece a staff consisting of 2 bars, or the entire piece a staff consisting of 3 bars. I want the same as you can see in the picture. How can I arrange this in musescore?

I hope you will understand 🙂. Hope to hear from you soon!

Kind regards,

David