Config keeps changing while online

1) you are not using in steam, if it is in steam, this problem won't occur...
2) thats the server binding or something... some server use some differnt game modes like placing a machine and all that, to use such functionality, some servers by default bind your keys...

To keep your config proper, you need to follow these below steps everytime...
1) open in-game console using ` button.
2) in that, type "unbindall" without quotes and press enter->close console later.
3) goto options->keyboard settings-> click use defaults button.