Maybe there are more an better options, but I can think of two:
- Create your own library. When you move a "default block" into your library, then modify the library block and then save it, I would expect it keep the "new default behaviour". Let me know if it doesn't work, it is quite some time I did something like that
- Create MATLAB Code that modifies setting you frequently want to modify. User "set_param", "gcb" and related commands and find reasonable ways to run the code (like shortcuts) when ever you need it
