Not sure if it's in the artist ver, but in the pro ver there is a signature track you can open. Pressing F1 and search for;
Signature Track
Studio One has a dedicated Signature Track which can be used to define the global time signature and key signature for the Song. You can also use it to change the time signature or key signature for any bar in the Song, as well as edit or remove them.
Click the Signature Track icon above the Arrange view to open the Signature Track. This reveals the time / key signature markers
