Hello there.
I have looked deep in my 3650 settings but i could not find a way to change the screensaver. It has 2 options - Text and Date/Time. Is there a way to set any other screensaver? What file extension should it be?
I dont even know if that is possible...

You might want to try downloading a program called SCREEN SAVER. It offers some variations from the default SS from your phone. If you have a bluetooth that is.