Default [Q] Registry change problems

I have tried different reg editors to change settings but get message access denied.I recently tried to update the Net framework version to 3.5 by installing the Cab file and going to the reg editor and setting the 2 versions by changing the 0 and 1 around but again access denied.I used a configuration program and set it to run the new version,( 3,5 which it sees) pushed apply and closed but when i look at the reg editior the old version is still set to 1,and the new version 0.I have done these chages,soft reset etc but nothing changes