I am new to rhino so this is probably a very basic question: How can I change a model in Rhino without deleting and doing it all over? Let´s say I draw a chair and I want to change the radius of a fillet, the dimension of the seat, thickness of the legs etc. I am working on my mac. I have seen that there is a direct command on the windows version of rhino where it seems it is easy to do these changes, but I cannot find it on my mac version of rhino.
I would also like to get tips on how to make several versions based on the same model changing it organically by drag, push and pull.
If there is a tutorial/ instruction video on these topics I would like to know.