Google suggests that there is no option other than to delete it and then redraw..http://graphicdesign.stackexchange.com/questions/559/is-it-possible-to-modify-a-rounded-re ctangles-radius-in-photoshop but I find this a big time waster as I'll then have to redo all the colours and strokes
and all other changes i've made such as perspective and so on.
I'm sure someone here has the solution.
Or, as a work around, create the rectangle in illustrator, where you can edit it easily, then when you like it, copy it and paste it into Photoshop as a Smart Vector layer. If you need to change, just edit the Smart layer or delete it and past in a new one. That's what I always do
Thanks so much! Really appreciated.