Aircraft noice is dimished after installing through steam

[softsol12 10]

Hi I Downloaded Arma 2 / Arrowhead from Steam and I noticed that the noise of the aircrafts is not the same as it was with my Arma2 hardcopy install, it is much more quieter and you cannot see the red hot heat coming from the Figheter Jets pipes anymore. Steam suggested the below:

Hello Sacha, Please try the following: Exit Steam entirely. Browse to your Steam installation (Usually C:\Program Files\Steam\) Rename the "steamapps" folder to "old_steamapps" Re-launch Steam and re-install the game. Once the installation is complete, test the issue. If the issue is not resolved, you can rename the folder back to avoid having to re-install other games

However the game is telling me i do not have permission to change the name etc. What can I do to get back the orginal sounds of all aircrafts? Thanks

[demonized 20]

steam.........