Hello old pickle, firstly, I'll ask, do you have the user manual for the camera?
The mz-60 has the option of fully manual, Tv mode (shutter priority) and Av (aperture priority) modes.
I suspect the step you're missing is setting the mode using the button on the top of the camera to Av, Tv or M before you're trying to adjust the appropriate parameter. Have a good read of the manual, it will help. If you don't have the manual, a quick search of the internet turned up this link:
http://dl.owneriq.net/4/4846fa21-0be...454e443047.pdf
Pages 64 to 69 detail Av, Tv and M modes.
Hope this helps.