autoexec_client.cfg is your main config file (outside settings_ddnet.cfg), the rest can be placed wherever you want as long as the exec commands calling them are correct
whatever commands you put in there will be ran on startup
21:34
so if you want deepfly to default to off you'd do something like exec disable_deepfly.cfg in there
21:35
If you just want to remember the state when you close the game you can go without the autoexec_client.cfg, then your settings file will store the settings