Scribe elements that you have added to the canvas will be drawn in the order that they appear in the timeline at the bottom. If you need to make space on the canvas for the new elements, the only way to do this is to select all the elements you need to move and move them on the canvas. Once they are selected, this can be done using the arrow keys on your keyboard.

Then, get the camera into the position on the canvas you would like to add the elements, select the (single) element in the timeline that the elements will be drawn after and then add the new elements to the canvas. When an element is selected, any new element that is added will appear immediately after that element in the timeline and on the area of the canvas that is currently being viewed.