Did you use the CVAR configurator? If not, download it and use it. When you're done, click choose directory and drop it into Crysis 3. If you're making changes to an existing auto exec file, make sure the file isn't write protected.
Binding keys in the autoexec.cfg.how is it done, exactly? In you crysis folder, if not already present create, otherwise find the autoexec.cfg. For Crysis on the PC, a GameFAQs message board topic titled 'Where am I supposed to create the System.cfg file. Need to be used in an autoexec.cfg instead.
Right click/properties/attributes/uncheck read only. Also check the file type. Theres an autoexec file which is the cfg (configuration) file and theres a file called autoexec.cfg which is a bak (backup) file.
Autoexec Cfg
Crysis 3 Walkthrough
You need to make your changes in the autoexec file which will in turn copy them into your backup file when you run the game. Don't ask me why the file extensions are retarded but they are.
Autoexec.cfg Dota 2
Imho stealth mode got fked up bit too much c3 mp.