On the 'Main Menu' select 'Options.'
Here you can change your 'Game Play' that you were referring to as well as your 'Sounds' and 'Graphic Settings.'
You can use any of the 'Career' settings and they will go to a default setting in Game Play' options.
You can then customise the settings in 'Game Play' to what you want.
After you have selected your mission and before you start your patrol check that your 'Game Play' settings are still as you left them.
If you have problems see my Tutorial Post #12
http://www.subsim.com/radioroom/showthread.php?t=211804