Backup your settings before verifying game files.

[ACE-OF-ACES]

Remember there are two locations, and some files get copied to both, but only used from one.. Basically the USER folder and GAME INSTALL folder, i.e.

USER
C:\Users\<YOUR USER NAME HERE>\Documents\1C SoftClub\il-2 sturmovik cliffs of dover

GAME INSTALL
C:\Program Files (x86)\Steam\SteamApps\common\il-2 sturmovik cliffs of dover

What I found was all the *.ini & *.log files in the GAME INSTALL folder are not used..

I even deleted them to prove it to myself.

Where as the *.ini & *.log files in your USER folder are used..

And those are the ones you want to make back ups of from time to time.