"Note: You cannot change the corner radius after you’ve drawn a rounded rectangle. If you feel that you might need to change the corner radius, draw a normal rectangle and choose Effect > Convert to Shape > Rounded Rectangle and specify the rounded rectangle parameters. To modify the corner radius or other parameters modify the effect parameters from the Appearance panel."
This is hilarious. Every drawing program on the planet (including MS WORD, which is a type program) allows you to adjust the corner radius once a rectangle shape has been drawn. Massively dropped ball, Adobe, especially since this has not even been addressed in CS6.
But never fear, digabyte; ever-vigilant, Adobe is already on it! After all, your non-question has been promptly transferred to Illustrator's user-to-user forum so it can be non-answered by other users just like you who are powerless to do anything about it.
See? Problem solved!
Every drawing program on the planet...allows you to adjust the corner radius once a rectangle shape has been drawn.
Egads, man, are you daft?! If Illustrator were to allow you to change the parameters of basic geometric primitives (radii of corners, number of points on a star, sides of a polygon, arc of an ellipse...) like all its amaturish competitors can do, it would risk loosing the mystique it enjoys as the leading professional drawing program which it derives from the necessity to perform clever and convoluted esoteric workarounds for every little common thing.
You're obvously a rank beginner. Every real Illustrator user knows that any change to the program from the way it currently is would herald the very end of western civilization as we know it...unless and until it happens, at which point it will be okay because it will then be part of the way Illustrator works and therefore worthy of the highest praise for Adobe's ground-breaking innovation.
After all, although it took two decades, Adobe stuck with it and came through and invented the concept of page 2 in a drawing program. And the ability to break a path at several selected anchors at once! And to...get this...align multiple anchors! Yes, the breakthrough innovation never stops here.
So please don't mention user-defined drawing scales, or connector lines, or dimension tools, or inline graphics, or auto-fitting textframes or any of that other stuff that amateurish programs do. You'll only further reveal your ignorance of the fact that those things are clearly the work of the devil...unless and until they are invented by Adobe Illustrator, the only professional drawing tool..
Hope this helps.
Glad I could get you on track, digabyte, and that your blatent naiveté has been nipped in the bud. I mean, had you been allowed to continue uncorrected there's no telling where this might have gone. You might next make the ridiculous assertion that Illustrator's Knife Tool should actually be able to cut its own open unfilled paths! That could be bloody.
Boy do I miss FreeHand. Not only did FreeHand allow you edit corner radii post facto, but you also had much more interactive control of polygons and stars and such. It appears Illustrator CC has NOT fixed this issue. And apparently even Photoshop CC now has the ability to edit rounded corners.
Or if Adobe really wanted to show that mastery of software, they might allow the ridiculously 'archaic' Arc tool to specify start and end angles! It's such an obvious requirement of any arc drawing tool. I was using drawing programs in 1992 that let me do that, and 21 YEARS later Illustrator STILL can't do it. CorelDraw has provided this for over 10 years to my certain knowledge. Just try drawing a triangle with rounded corners (like a road sign)... oh the pain!