DutchFox wrote on Jan 20^th, 2017 at 7:54pm:

Only got the 707 yesterday and figured it wouldn't make sense to start another topic on the same issue. It's a minor issue but I'd still like to get everything out of this bird!  ;D I tried everything mentioned above however still no switch or crew sounds are working, does anyone maybe have another suggestion on this?

If you just got it it should work. I had a severely outdated version and it did it. When you install the 707, you'll see a command prompt at the end of the installation appear for a second. It says something sound fix. This used to be a problem with all CS planes. Least the ones I've used in the past.

I read somewhere on these forums I believe that there's a .bat file that fixes it. CS team just integrated it into the installation.

So only way I can see to fix it is 1, reinstall and see if the command prompt appears, if it doesn't search for the sound fix.

PS: There is a temporary fix. After you load a flight open the toolbar and go select aircraft, when it opens press enter and it should work. Least on the ground. I've noticed that that method stops working in the air.