SU0 maintain defaults only
SU1 maintain adress only
SU2 maintain parameters only
SU3 maintain address, defaults and parameters
If you want to further restrict these transactions you have to create transaction variants (= addidional transactions) or transaction standard variants (=modification of the original transactions) using transaction SHD0.
Using SHD0 you can turn input fields into display fields, hide fields or set default values for input fields fon any transaction.
Thanks & Regards,
Ankit