how to Change rehearsal marck from rectangle to square in dorico element
Welcome to the forum, @Paul_Pontbriand!
The enclosure type is set in Engraving Options, and since Elements doesn’t give you access to Engraving Options, you’re not able to change it.
However, even in Pro you can’t choose a square – just rectangle, rounded rectangle, circle, or no enclosure. (Although there’s probably some way of faking it with the minimum height/width settings.)