This is normal behavior of most cameras. They have initial starting values which are used when you connect the camera.
Now if you start MATLAB and change those parameters the camera will run with the parameters as long as its connected to that MATLAB script/function. If you clear the camera object and reinitialize it, the standart parameters will be loaded again.
If you disconnect the camera or close MATLAB you also delete the camera object and so the camera will load the default parameters the next time.
You can try to change the parameter by accessing the camera configuration (mostly with a developer SDK or a camera driver, config file or something like that). If you have no information about that try to contact the manufacturer of the camera and ask for instructions to change those parameters.
EDIT: You could also store those values into a config file yourself and everytime the camera loads you automatically give the parameters to the camera (similar like you doing now, initialize the camera and then change the parameters, just with a pre-defined config file)
