Hey, if you are playing single player, then it should save each time you start a new campaign day, otherwise, you can adjust your Arma difficulty settings to allow saving when ever you like (instead of just once)

Hope this helps

I mean when i close Arma

Same issue, After closing the game and reopening TRGM2 saves are gone? and it auto-starts me at the beginning again. same goes for every map variant released for me