[edwinvega86]

I know that customers can save in the cookie, but can the server save the game settings in the cookie? or is there any method?

[impossible_cc]

You can use convar instead

[edwinvega86]

yes but how could the cvar configurator be maintained for the next map, in my case it always resets on each map.

[GetRektByNoob]

I'm not sure if there an easier way or if it's possible in L4D2 but you can try to create keyvalue file and save the convar value in it on OnMapEnd and on OnMapStart you can read the file and load the file and save the value.
double check that forwards because I'm not sure if this is the correct name.

[Marttt]

cvar configs (different from the default value) should be put on the server.cfg file
if your server has some kind of different configs based on player count or difficult setting, you should look for a plugin that runs a .cfg file that depends on the config