Unix format in gVim

I need to be very careful to keep ^M characters out of files.
In gVim, I can change the file format to Unix easily enough, but is there any way to make Unix the default format?

I can see "startup options" in the menu, but this takes me to some meaningless config file. I believe my config value should be added in here, but I don't know what I need to add

Thanks

You need to add "unix" to the "sessionoptions" option. Full information avalable at
Vim documentation: options